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    <title>DEV Community: refaat Al Ktifan</title>
    <description>The latest articles on DEV Community by refaat Al Ktifan (@refaatalktifan).</description>
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    <item>
      <title>OpenTelemetry in Production: Traces, Context, and What Actually Matters</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Tue, 28 Apr 2026 17:48:50 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/opentelemetry-in-production-traces-context-and-what-actually-matters-20f5</link>
      <guid>https://dev.to/refaatalktifan/opentelemetry-in-production-traces-context-and-what-actually-matters-20f5</guid>
      <description>&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fpfu82kdtl6fh2kihvpzn.png" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fpfu82kdtl6fh2kihvpzn.png" alt="Oronts OpenTelemetry in Production" width="800" height="533"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;h2&gt;
  
  
  Why OpenTelemetry Won
&lt;/h2&gt;

&lt;p&gt;Three years ago, the observability landscape was fragmented. Jaeger for tracing, Prometheus for metrics, Fluentd for logs, each with its own SDK, its own protocol, its own vendor lock-in. OpenTelemetry unified them into a single standard: one SDK, one protocol (OTLP), one collector that routes to any backend.&lt;/p&gt;

&lt;p&gt;We adopted OpenTelemetry across our production systems. This article covers the patterns that actually matter in production, not the setup tutorial. For the broader observability strategy (when to alert, what to log, how to structure metrics), see our &lt;a href="https://oronts.com/en/guides/ai-observability" rel="noopener noreferrer"&gt;AI observability guide&lt;/a&gt;. This article goes deeper on OpenTelemetry-specific implementation.&lt;/p&gt;

&lt;h2&gt;
  
  
  Context Propagation: The Hardest Part
&lt;/h2&gt;

&lt;p&gt;A single user request might cross 5 services, 3 message queues, 2 worker processes, and an LLM call. Context propagation ensures that the trace follows the request across all of them.&lt;/p&gt;

&lt;h3&gt;
  
  
  HTTP Propagation (Easy)
&lt;/h3&gt;

&lt;p&gt;OpenTelemetry auto-instruments HTTP clients and servers. The trace context propagates via &lt;code&gt;traceparent&lt;/code&gt; and &lt;code&gt;tracestate&lt;/code&gt; headers. This works out of the box.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="c1"&gt;// Auto-instrumented: no code needed for HTTP propagation&lt;/span&gt;
&lt;span class="c1"&gt;// The SDK adds traceparent header to outgoing requests&lt;/span&gt;
&lt;span class="c1"&gt;// The receiving service extracts it and continues the trace&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  Queue Propagation (Hard)
&lt;/h3&gt;

&lt;p&gt;Message queues break automatic propagation. When you enqueue a message, the trace context must be serialized into the message headers. When a worker dequeues it, the context must be extracted and the trace continued.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="c1"&gt;// Producer: inject trace context into message headers&lt;/span&gt;
&lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;propagation&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@opentelemetry/api&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;enqueueMessage&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;queue&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;payload&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;any&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;carrier&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;Record&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{};&lt;/span&gt;
    &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;inject&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;active&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt; &lt;span class="nx"&gt;carrier&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

    &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;messageQueue&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;send&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;queue&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="na"&gt;body&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;payload&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="na"&gt;headers&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;carrier&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="c1"&gt;// Contains traceparent, tracestate&lt;/span&gt;
    &lt;span class="p"&gt;});&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="c1"&gt;// Consumer: extract trace context from message headers&lt;/span&gt;
&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;processMessage&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;message&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;QueueMessage&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;parentContext&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;extract&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;active&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt; &lt;span class="nx"&gt;message&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;headers&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

    &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;with&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;parentContext&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="k"&gt;async &lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;span&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;startSpan&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;process_message&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="na"&gt;attributes&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
                &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;messaging.system&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;rabbitmq&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;messaging.operation&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;process&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;messaging.destination&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;message&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;queue&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="p"&gt;},&lt;/span&gt;
        &lt;span class="p"&gt;});&lt;/span&gt;

        &lt;span class="k"&gt;try&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nf"&gt;handleMessage&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;message&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;body&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
            &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setStatus&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt; &lt;span class="na"&gt;code&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;SpanStatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;OK&lt;/span&gt; &lt;span class="p"&gt;});&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;catch &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;error&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setStatus&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt; &lt;span class="na"&gt;code&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;SpanStatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;ERROR&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="na"&gt;message&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;error&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;message&lt;/span&gt; &lt;span class="p"&gt;});&lt;/span&gt;
            &lt;span class="k"&gt;throw&lt;/span&gt; &lt;span class="nx"&gt;error&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;finally&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;end&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;});&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This pattern works for RabbitMQ, Kafka, BullMQ, SQS, and Symfony Messenger. The message headers carry the trace context. The consumer extracts it and creates child spans under the original trace.&lt;/p&gt;

&lt;h3&gt;
  
  
  Worker Process Propagation
&lt;/h3&gt;

&lt;p&gt;For Vendure's BullMQ workers, Pimcore's Symfony Messenger workers, and similar background job systems, the pattern is the same: serialize context into the job payload, extract on the worker side.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="c1"&gt;// BullMQ: add trace context to job data&lt;/span&gt;
&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;addJob&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;queue&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Queue&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;data&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;any&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;carrier&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;Record&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{};&lt;/span&gt;
    &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;inject&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;active&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt; &lt;span class="nx"&gt;carrier&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

    &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;queue&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;add&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;process&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="p"&gt;...&lt;/span&gt;&lt;span class="nx"&gt;data&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="na"&gt;_traceContext&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;carrier&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="p"&gt;});&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="c1"&gt;// BullMQ: extract trace context in worker&lt;/span&gt;
&lt;span class="nx"&gt;worker&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;on&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;process&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="k"&gt;async &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;job&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;parentContext&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;extract&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;active&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt; &lt;span class="nx"&gt;job&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;data&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;_traceContext&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="p"&gt;{});&lt;/span&gt;

    &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;with&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;parentContext&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="k"&gt;async &lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;span&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;startSpan&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;`job:&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;job&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;name&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;`&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="k"&gt;try&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nf"&gt;processJob&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;job&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;data&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;finally&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;end&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;});&lt;/span&gt;
&lt;span class="p"&gt;});&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Tracing LLM Calls
&lt;/h2&gt;

&lt;p&gt;LLM calls are the most expensive operations in AI systems. Tracing them with proper attributes enables cost tracking, latency analysis, and quality monitoring.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;tracedLlmCall&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;prompt&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;LlmOptions&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;span&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;tracer&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;startSpan&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.generate&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="na"&gt;attributes&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.provider&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;provider&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;           &lt;span class="c1"&gt;// "openai", "anthropic"&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.model&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;model&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;                 &lt;span class="c1"&gt;// "gpt-4o", "claude-sonnet-4-20250514"&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.temperature&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;temperature&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.max_tokens&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;maxTokens&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.prompt_tokens&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nf"&gt;estimateTokens&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;prompt&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt; &lt;span class="c1"&gt;// estimate before call&lt;/span&gt;
        &lt;span class="p"&gt;},&lt;/span&gt;
    &lt;span class="p"&gt;});&lt;/span&gt;

    &lt;span class="k"&gt;try&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;response&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;llmClient&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;generate&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;prompt&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

        &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttributes&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.response_tokens&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;usage&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;completionTokens&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.total_tokens&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;usage&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;totalTokens&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.finish_reason&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;finishReason&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.cost_usd&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nf"&gt;calculateCost&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;usage&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;model&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
        &lt;span class="p"&gt;});&lt;/span&gt;

        &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setStatus&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt; &lt;span class="na"&gt;code&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;SpanStatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;OK&lt;/span&gt; &lt;span class="p"&gt;});&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nx"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;text&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;catch &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;error&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setStatus&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt; &lt;span class="na"&gt;code&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;SpanStatusCode&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;ERROR&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="na"&gt;message&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;error&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;message&lt;/span&gt; &lt;span class="p"&gt;});&lt;/span&gt;
        &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;llm.error_type&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;error&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="kd"&gt;constructor&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;name&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="k"&gt;throw&lt;/span&gt; &lt;span class="nx"&gt;error&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;finally&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;end&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;&lt;strong&gt;Do NOT put prompt text in span attributes.&lt;/strong&gt; Prompts contain PII. Span attributes are sent to your observability backend (Jaeger, Grafana Tempo, Datadog). Instead, log the prompt hash or token count. For the full PII-safe logging architecture, see our &lt;a href="https://oronts.com/en/guides/ai-data-leakage-prevention" rel="noopener noreferrer"&gt;AI data leakage guide&lt;/a&gt;.&lt;/p&gt;

&lt;h3&gt;
  
  
  LLM Span Attributes Convention
&lt;/h3&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Attribute&lt;/th&gt;
&lt;th&gt;Type&lt;/th&gt;
&lt;th&gt;Example&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.provider&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;string&lt;/td&gt;
&lt;td&gt;"openai"&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.model&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;string&lt;/td&gt;
&lt;td&gt;"gpt-4o"&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.temperature&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;float&lt;/td&gt;
&lt;td&gt;0.7&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.prompt_tokens&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;int&lt;/td&gt;
&lt;td&gt;1250&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.response_tokens&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;int&lt;/td&gt;
&lt;td&gt;340&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.total_tokens&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;int&lt;/td&gt;
&lt;td&gt;1590&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.finish_reason&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;string&lt;/td&gt;
&lt;td&gt;"stop"&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.cost_usd&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;float&lt;/td&gt;
&lt;td&gt;0.023&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.error_type&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;string&lt;/td&gt;
&lt;td&gt;"RateLimitError"&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;code&gt;llm.cache_hit&lt;/code&gt;&lt;/td&gt;
&lt;td&gt;boolean&lt;/td&gt;
&lt;td&gt;false&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;h2&gt;
  
  
  Sampling Strategies
&lt;/h2&gt;

&lt;p&gt;In high-volume AI systems, tracing every request is too expensive. Sampling reduces volume while preserving visibility into important traces.&lt;/p&gt;

&lt;h3&gt;
  
  
  Head-Based Sampling
&lt;/h3&gt;

&lt;p&gt;Decide at the start of the trace whether to sample it. Simple but lossy.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="c1"&gt;// Sample 10% of all traces&lt;/span&gt;
&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;sampler&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;TraceIdRatioBased&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mf"&gt;0.1&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

&lt;span class="c1"&gt;// Always sample errors (override ratio for error traces)&lt;/span&gt;
&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;compositeSampler&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;ParentBasedSampler&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
    &lt;span class="na"&gt;root&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;TraceIdRatioBased&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="mf"&gt;0.1&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
    &lt;span class="c1"&gt;// Errors always sampled via span processor&lt;/span&gt;
&lt;span class="p"&gt;});&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  Tail-Based Sampling (Recommended for AI)
&lt;/h3&gt;

&lt;p&gt;Decide after the trace completes whether to keep it. Keeps all interesting traces (errors, slow responses, high cost) and drops routine ones.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="c1"&gt;// OpenTelemetry Collector: tail-based sampling config&lt;/span&gt;
&lt;span class="nx"&gt;processors&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
    &lt;span class="nx"&gt;tail_sampling&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
        &lt;span class="nx"&gt;decision_wait&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;10&lt;/span&gt;&lt;span class="nx"&gt;s&lt;/span&gt;
        &lt;span class="nx"&gt;policies&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
            &lt;span class="err"&gt;#&lt;/span&gt; &lt;span class="nx"&gt;Keep&lt;/span&gt; &lt;span class="nx"&gt;all&lt;/span&gt; &lt;span class="nx"&gt;errors&lt;/span&gt;
            &lt;span class="o"&gt;-&lt;/span&gt; &lt;span class="nx"&gt;name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;errors&lt;/span&gt;
              &lt;span class="kd"&gt;type&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;status_code&lt;/span&gt;
              &lt;span class="nx"&gt;status_code&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nl"&gt;status_codes&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="nx"&gt;ERROR&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt;

            &lt;span class="err"&gt;#&lt;/span&gt; &lt;span class="nx"&gt;Keep&lt;/span&gt; &lt;span class="nx"&gt;slow&lt;/span&gt; &lt;span class="nf"&gt;traces &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;5&lt;/span&gt; &lt;span class="nx"&gt;seconds&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="o"&gt;-&lt;/span&gt; &lt;span class="nx"&gt;name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;slow&lt;/span&gt;
              &lt;span class="kd"&gt;type&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;latency&lt;/span&gt;
              &lt;span class="nx"&gt;latency&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nl"&gt;threshold_ms&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;5000&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt;

            &lt;span class="err"&gt;#&lt;/span&gt; &lt;span class="nx"&gt;Keep&lt;/span&gt; &lt;span class="nx"&gt;expensive&lt;/span&gt; &lt;span class="nx"&gt;LLM&lt;/span&gt; &lt;span class="nf"&gt;calls &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;$0&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="mi"&gt;10&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
            &lt;span class="o"&gt;-&lt;/span&gt; &lt;span class="nx"&gt;name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;expensive_llm&lt;/span&gt;
              &lt;span class="kd"&gt;type&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;string_attribute&lt;/span&gt;
              &lt;span class="nx"&gt;string_attribute&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                  &lt;span class="nx"&gt;key&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;llm&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;cost_usd&lt;/span&gt;
                  &lt;span class="nx"&gt;values&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[]&lt;/span&gt;  &lt;span class="err"&gt;#&lt;/span&gt; &lt;span class="nx"&gt;Custom&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;filter&lt;/span&gt; &lt;span class="k"&gt;in&lt;/span&gt; &lt;span class="nx"&gt;pipeline&lt;/span&gt;
                  &lt;span class="nx"&gt;enabled_regex_matching&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kc"&gt;true&lt;/span&gt;

            &lt;span class="err"&gt;#&lt;/span&gt; &lt;span class="nx"&gt;Sample&lt;/span&gt; &lt;span class="mi"&gt;5&lt;/span&gt;&lt;span class="o"&gt;%&lt;/span&gt; &lt;span class="k"&gt;of&lt;/span&gt; &lt;span class="nx"&gt;everything&lt;/span&gt; &lt;span class="k"&gt;else&lt;/span&gt;
            &lt;span class="o"&gt;-&lt;/span&gt; &lt;span class="nx"&gt;name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;baseline&lt;/span&gt;
              &lt;span class="kd"&gt;type&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;probabilistic&lt;/span&gt;
              &lt;span class="nx"&gt;probabilistic&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nl"&gt;sampling_percentage&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;5&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Tail-based sampling requires the OpenTelemetry Collector. The collector buffers complete traces, evaluates policies, and forwards only sampled traces to the backend. This adds latency (the &lt;code&gt;decision_wait&lt;/code&gt; period) but dramatically reduces storage costs while keeping all interesting data.&lt;/p&gt;

&lt;h2&gt;
  
  
  Privacy-Safe Spans
&lt;/h2&gt;

&lt;p&gt;Span attributes, span names, and span events are all sent to your observability backend. If any of these contain PII, your tracing infrastructure becomes a data protection liability.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="c1"&gt;// BAD: PII in span attributes&lt;/span&gt;
&lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;user.email&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;sara.mustermann@beispiel.de&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
&lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;user.name&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;Sara Mustermann&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
&lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;request.body&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;JSON&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;stringify&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;requestBody&lt;/span&gt;&lt;span class="p"&gt;));&lt;/span&gt; &lt;span class="c1"&gt;// Contains PII&lt;/span&gt;

&lt;span class="c1"&gt;// GOOD: token IDs and aggregate data only&lt;/span&gt;
&lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;user.id&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;usr_abc123&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;  &lt;span class="c1"&gt;// Opaque ID, not PII&lt;/span&gt;
&lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;entities.detected&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;3&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
&lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;entities.types&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;person&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;email&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;phone&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;]);&lt;/span&gt;
&lt;span class="nx"&gt;span&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setAttribute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;policy.applied&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;german-support&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Rules for privacy-safe tracing:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;User IDs: opaque identifiers only (not emails, not names)&lt;/li&gt;
&lt;li&gt;Request bodies: never include raw content. Log entity counts and types.&lt;/li&gt;
&lt;li&gt;LLM prompts: never include. Log token counts and prompt hash.&lt;/li&gt;
&lt;li&gt;Error messages: sanitize before attaching to spans. Strip any user data.&lt;/li&gt;
&lt;/ul&gt;

&lt;h2&gt;
  
  
  The Baggage API
&lt;/h2&gt;

&lt;p&gt;OpenTelemetry Baggage carries key-value pairs across service boundaries. Unlike span attributes (which stay on the span), baggage propagates to all downstream services automatically.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;baggage&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@opentelemetry/api&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

&lt;span class="c1"&gt;// Set baggage at the API gateway&lt;/span&gt;
&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;bag&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;createBaggage&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;tenant.id&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;value&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;tenant_acme&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt; &lt;span class="p"&gt;},&lt;/span&gt;
    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;request.priority&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;value&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;high&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt; &lt;span class="p"&gt;},&lt;/span&gt;
    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;feature.flags&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;value&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;new-checkout,beta-search&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt; &lt;span class="p"&gt;},&lt;/span&gt;
&lt;span class="p"&gt;});&lt;/span&gt;
&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;ctx&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;setBaggage&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;active&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt; &lt;span class="nx"&gt;bag&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

&lt;span class="c1"&gt;// Downstream services can read baggage&lt;/span&gt;
&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;tenantId&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;propagation&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getBaggage&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;active&lt;/span&gt;&lt;span class="p"&gt;())?.&lt;/span&gt;&lt;span class="nf"&gt;getEntry&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;tenant.id&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;)?.&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Useful for:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Tenant ID propagation (every downstream service knows which tenant)&lt;/li&gt;
&lt;li&gt;Feature flags (propagate experiment assignments across services)&lt;/li&gt;
&lt;li&gt;Priority routing (high-priority requests get different queue treatment)&lt;/li&gt;
&lt;li&gt;Debug markers (mark specific requests for verbose logging)&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Baggage travels with the trace context in HTTP headers and message metadata. Every service that extracts the trace context also gets the baggage.&lt;/p&gt;

&lt;h2&gt;
  
  
  Collector Architecture
&lt;/h2&gt;

&lt;p&gt;The OpenTelemetry Collector is the central routing layer between your applications and your observability backends.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;┌─────────────┐  ┌─────────────┐  ┌─────────────┐
│  Service A   │  │  Service B   │  │  Worker C    │
│  (OTLP gRPC) │  │  (OTLP HTTP) │  │  (OTLP gRPC) │
└──────┬───────┘  └──────┬───────┘  └──────┬───────┘
       │                 │                 │
       ▼                 ▼                 ▼
┌─────────────────────────────────────────────────┐
│              OTel Collector                      │
│                                                  │
│  Receivers: OTLP (gRPC + HTTP)                  │
│  Processors: batch, tail_sampling, attributes    │
│  Exporters: Tempo, Prometheus, Loki             │
└─────────────────────────────────────────────────┘
       │                 │                 │
       ▼                 ▼                 ▼
┌──────────────┐ ┌──────────────┐ ┌──────────────┐
│  Grafana     │ │  Prometheus  │ │  Grafana     │
│  Tempo       │ │              │ │  Loki        │
│  (traces)    │ │  (metrics)   │ │  (logs)      │
└──────────────┘ └──────────────┘ └──────────────┘
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The collector handles batching (reduces network calls), sampling (reduces storage), attribute processing (adds/removes attributes), and routing (different signals to different backends). Deploy it as a sidecar or as a central service depending on your infrastructure.&lt;/p&gt;

&lt;p&gt;For &lt;a href="https://dev.to/cloud"&gt;cloud deployment&lt;/a&gt; patterns including observability infrastructure, that page covers our approach.&lt;/p&gt;

&lt;h2&gt;
  
  
  Common Pitfalls
&lt;/h2&gt;

&lt;ol&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;No context propagation across queues.&lt;/strong&gt; HTTP propagation is automatic. Queue propagation is not. If you don't inject/extract context in message headers, traces break at every queue boundary.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;PII in span attributes.&lt;/strong&gt; Your tracing backend indexes everything. If spans contain emails, names, or request bodies, your Grafana Tempo cluster is a PII store.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Tracing every request in production.&lt;/strong&gt; At 1000 RPS, full tracing generates terabytes of data. Use tail-based sampling to keep errors, slow traces, and expensive operations.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;No LLM-specific attributes.&lt;/strong&gt; Without token counts, cost, model ID, and finish reason on LLM spans, you can't track AI costs or diagnose quality issues.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Head-based sampling dropping errors.&lt;/strong&gt; If you sample 10% of traces and an error happens in the 90% you drop, you never see it. Use tail-based sampling or always-sample-errors policies.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Baggage for large payloads.&lt;/strong&gt; Baggage travels with every request. Large values increase header size on every HTTP call. Keep baggage values small (IDs, flags, priorities).&lt;/p&gt;&lt;/li&gt;
&lt;/ol&gt;

&lt;h2&gt;
  
  
  Key Takeaways
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Context propagation across queues is the hardest part.&lt;/strong&gt; HTTP is automatic. Queues require manual inject/extract of trace context in message headers. This is where most distributed tracing implementations break.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Trace LLM calls with cost and token attributes.&lt;/strong&gt; Model, provider, token counts, cost, finish reason. These attributes enable AI cost dashboards and quality monitoring.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Tail-based sampling for AI workloads.&lt;/strong&gt; Keep all errors, slow traces, and expensive operations. Drop routine traces. Reduces storage by 90%+ while keeping all interesting data.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;No PII in spans.&lt;/strong&gt; Opaque user IDs, entity counts, token types. Never raw content, emails, names, or request bodies.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Baggage propagates tenant context.&lt;/strong&gt; Set tenant ID, feature flags, and priority at the edge. Every downstream service reads it from baggage without explicit parameter passing.&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

</description>
      <category>opentelemetry</category>
      <category>observability</category>
      <category>devops</category>
      <category>monitoring</category>
    </item>
    <item>
      <title>AI Browser Automation Without BrowserBase: What We Built Instead</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sat, 25 Apr 2026 15:17:00 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/ai-browser-automation-without-browserbase-what-we-built-instead-34p</link>
      <guid>https://dev.to/refaatalktifan/ai-browser-automation-without-browserbase-what-we-built-instead-34p</guid>
      <description>&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fi7t9h76q858biofeoz27.png" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fi7t9h76q858biofeoz27.png" alt="Oronts Automation" width="800" height="533"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;h2&gt;
  
  
  The Paid Browser Automation Market
&lt;/h2&gt;

&lt;p&gt;BrowserBase, Browserless, and similar services charge per-minute or per-session for managed headless browsers. For AI workflows that need to interact with web pages (filling forms, extracting structured data, navigating multi-step processes), these services handle the infrastructure: browser instances, anti-detection, proxies, and session management.&lt;/p&gt;

&lt;p&gt;The pricing adds up fast. At $0.10-0.50 per session-minute, a workflow that processes 1,000 pages per day at 2 minutes each costs $200-1,000 per day. For an AI system that runs continuously, that's $6,000-30,000 per month just for browser infrastructure.&lt;/p&gt;

&lt;p&gt;We built a self-hosted alternative using Playwright + LLM for page understanding. It handles 90% of the use cases at a fraction of the cost. This article covers the architecture. For how we build &lt;a href="https://oronts.com/en/guides/ai-workflow-design" rel="noopener noreferrer"&gt;AI workflow systems&lt;/a&gt; and &lt;a href="https://oronts.com/en/guides/agentic-ai-systems" rel="noopener noreferrer"&gt;agentic AI&lt;/a&gt; more broadly, those guides cover the higher-level patterns.&lt;/p&gt;

&lt;h2&gt;
  
  
  The Architecture
&lt;/h2&gt;



&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;┌─────────────────────────────────────────────────────────┐
│                  AI Browser Engine                       │
│                                                          │
│  ┌──────────────┐  ┌──────────────┐  ┌──────────────┐  │
│  │  Task Queue   │  │  Instance    │  │  Session      │  │
│  │  (BullMQ)     │  │  Pool        │  │  Manager      │  │
│  │               │  │  (Playwright │  │  (cookies,    │  │
│  │  Prioritized  │  │   browsers)  │  │   localStorage│  │
│  │  Retry logic  │  │              │  │   auth state) │  │
│  └──────┬───────┘  └──────┬───────┘  └──────┬───────┘  │
│         │                 │                  │           │
│         ▼                 ▼                  ▼           │
│  ┌──────────────────────────────────────────────────┐   │
│  │              Page Interaction Layer                │   │
│  │                                                    │   │
│  │  1. Navigate to URL                               │   │
│  │  2. Wait for page load                            │   │
│  │  3. Extract page structure (accessibility tree)   │   │
│  │  4. Send structure to LLM for understanding       │   │
│  │  5. LLM returns action plan (click, type, select) │   │
│  │  6. Execute actions via Playwright                │   │
│  │  7. Extract structured data from result           │   │
│  └──────────────────────────────────────────────────┘   │
│                                                          │
└─────────────────────────────────────────────────────────┘
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Instance Pooling
&lt;/h2&gt;

&lt;p&gt;Running a new browser for every task is expensive (cold start: 1-3 seconds, memory: 200-400MB per instance). A pool reuses browser instances across tasks.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;BrowserPool&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="k"&gt;private&lt;/span&gt; &lt;span class="nx"&gt;available&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Browser&lt;/span&gt;&lt;span class="p"&gt;[]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;[];&lt;/span&gt;
    &lt;span class="k"&gt;private&lt;/span&gt; &lt;span class="nx"&gt;inUse&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nb"&gt;Map&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Browser&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
    &lt;span class="k"&gt;private&lt;/span&gt; &lt;span class="nx"&gt;maxInstances&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;number&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="nf"&gt;constructor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nl"&gt;maxInstances&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;number&lt;/span&gt; &lt;span class="p"&gt;})&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;maxInstances&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;maxInstances&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;

    &lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="nf"&gt;acquire&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Browser&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt; &lt;span class="nl"&gt;id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="c1"&gt;// Reuse an available instance&lt;/span&gt;
        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;available&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;length&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;available&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;pop&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;&lt;span class="o"&gt;!&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
            &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;id&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;crypto&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;randomUUID&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
            &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;inUse&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
            &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;id&lt;/span&gt; &lt;span class="p"&gt;};&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;

        &lt;span class="c1"&gt;// Create new if under limit&lt;/span&gt;
        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;inUse&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;size&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;&lt;/span&gt; &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;maxInstances&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;chromium&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;launch&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
                &lt;span class="na"&gt;headless&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kc"&gt;true&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="na"&gt;args&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;
                    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;--no-sandbox&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;--disable-setuid-sandbox&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;--disable-dev-shm-usage&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;--disable-gpu&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                    &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;--single-process&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="p"&gt;],&lt;/span&gt;
            &lt;span class="p"&gt;});&lt;/span&gt;
            &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;id&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;crypto&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;randomUUID&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
            &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;inUse&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
            &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;id&lt;/span&gt; &lt;span class="p"&gt;};&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;

        &lt;span class="c1"&gt;// Pool exhausted: wait for one to be released&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;Promise&lt;/span&gt;&lt;span class="p"&gt;((&lt;/span&gt;&lt;span class="nx"&gt;resolve&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;waitQueue&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;push&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;resolve&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="p"&gt;});&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;

    &lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="nf"&gt;release&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="k"&gt;void&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;inUse&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="o"&gt;!&lt;/span&gt;&lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;return&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

        &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;inUse&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="k"&gt;delete&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

        &lt;span class="c1"&gt;// Clear state between tasks&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;pages&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;contexts&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
        &lt;span class="k"&gt;for &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt; &lt;span class="k"&gt;of&lt;/span&gt; &lt;span class="nx"&gt;pages&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;close&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;

        &lt;span class="c1"&gt;// If someone is waiting, give them this instance&lt;/span&gt;
        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;waitQueue&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;length&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;resolve&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;waitQueue&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;shift&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;&lt;span class="o"&gt;!&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
            &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;newId&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;crypto&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;randomUUID&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
            &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;inUse&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;newId&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
            &lt;span class="nf"&gt;resolve&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="na"&gt;id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;newId&lt;/span&gt; &lt;span class="p"&gt;});&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;else&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;available&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;push&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  Pool Sizing
&lt;/h3&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Workload&lt;/th&gt;
&lt;th&gt;Pool Size&lt;/th&gt;
&lt;th&gt;Memory Required&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;Light (&amp;lt; 100 pages/hour)&lt;/td&gt;
&lt;td&gt;2-3 instances&lt;/td&gt;
&lt;td&gt;1-2 GB&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Medium (100-500 pages/hour)&lt;/td&gt;
&lt;td&gt;5-10 instances&lt;/td&gt;
&lt;td&gt;3-5 GB&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Heavy (500+ pages/hour)&lt;/td&gt;
&lt;td&gt;10-20 instances&lt;/td&gt;
&lt;td&gt;5-10 GB&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;p&gt;Each Chromium instance uses 200-400MB of RAM. The pool size determines your throughput ceiling and memory requirements. Start small and scale based on actual load.&lt;/p&gt;

&lt;h2&gt;
  
  
  Session Management
&lt;/h2&gt;

&lt;p&gt;Many workflows require maintaining login state across multiple page interactions. The session manager persists cookies, localStorage, and authentication tokens between tasks.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;SessionManager&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="k"&gt;private&lt;/span&gt; &lt;span class="nx"&gt;sessions&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nb"&gt;Map&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;SessionState&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;

    &lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="nf"&gt;createSession&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;SessionOptions&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="nx"&gt;BrowserContext&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;newContext&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
            &lt;span class="na"&gt;viewport&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;width&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;1280&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="na"&gt;height&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;720&lt;/span&gt; &lt;span class="p"&gt;},&lt;/span&gt;
            &lt;span class="na"&gt;userAgent&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;userAgent&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getRandomUserAgent&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt;
            &lt;span class="na"&gt;locale&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;locale&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;en-US&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="na"&gt;timezoneId&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;timezone&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;Europe/Berlin&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="p"&gt;});&lt;/span&gt;

        &lt;span class="c1"&gt;// Restore previous session state if exists&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;existing&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;sessions&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;existing&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;addCookies&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;existing&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;cookies&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
            &lt;span class="c1"&gt;// localStorage restored via page.evaluate after navigation&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;

        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;

    &lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="nf"&gt;saveSession&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;BrowserContext&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="k"&gt;void&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;cookies&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;cookies&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;pages&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;pages&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
        &lt;span class="kd"&gt;let&lt;/span&gt; &lt;span class="nx"&gt;localStorage&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{};&lt;/span&gt;

        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;pages&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;length&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="nx"&gt;localStorage&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;pages&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;].&lt;/span&gt;&lt;span class="nf"&gt;evaluate&lt;/span&gt;&lt;span class="p"&gt;(()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
                &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="na"&gt;data&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;Record&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{};&lt;/span&gt;
                &lt;span class="k"&gt;for &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="kd"&gt;let&lt;/span&gt; &lt;span class="nx"&gt;i&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt; &lt;span class="nx"&gt;i&lt;/span&gt; &lt;span class="o"&gt;&amp;lt;&lt;/span&gt; &lt;span class="nb"&gt;window&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;localStorage&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;length&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt; &lt;span class="nx"&gt;i&lt;/span&gt;&lt;span class="o"&gt;++&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
                    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;key&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nb"&gt;window&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;localStorage&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;key&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;i&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
                    &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;key&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="nx"&gt;data&lt;/span&gt;&lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="nx"&gt;key&lt;/span&gt;&lt;span class="p"&gt;]&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nb"&gt;window&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;localStorage&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getItem&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;key&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="dl"&gt;''&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
                &lt;span class="p"&gt;}&lt;/span&gt;
                &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nx"&gt;data&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
            &lt;span class="p"&gt;});&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;

        &lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;sessions&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;set&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="nx"&gt;cookies&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="nx"&gt;localStorage&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="na"&gt;lastUsed&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nb"&gt;Date&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;now&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt;
        &lt;span class="p"&gt;});&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  LLM-Driven Page Understanding
&lt;/h2&gt;

&lt;p&gt;The core innovation: instead of writing CSS selectors or XPath queries for every page, send the page's accessibility tree to an LLM and let it decide which elements to interact with.&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;extractPageStructure&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Page&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="c1"&gt;// Get the accessibility tree (structured, compact representation)&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;tree&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;accessibility&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;snapshot&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;

    &lt;span class="c1"&gt;// Convert to a text format the LLM can understand&lt;/span&gt;
    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nf"&gt;formatAccessibilityTree&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;tree&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="na"&gt;maxDepth&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;5&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="na"&gt;includeRoles&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;button&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;link&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;textbox&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;combobox&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;checkbox&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;heading&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
        &lt;span class="na"&gt;includeText&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kc"&gt;true&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
        &lt;span class="na"&gt;includeLabels&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kc"&gt;true&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="p"&gt;});&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;formatAccessibilityTree&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;any&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;any&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;depth&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="mi"&gt;0&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;depth&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;maxDepth&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="dl"&gt;''&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="o"&gt;!&lt;/span&gt;&lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;includeRoles&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;includes&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;role&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="o"&gt;&amp;amp;&amp;amp;&lt;/span&gt; &lt;span class="nx"&gt;depth&lt;/span&gt; &lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="c1"&gt;// Skip non-interactive elements, but recurse into children&lt;/span&gt;
        &lt;span class="k"&gt;return &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;children&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="p"&gt;[]).&lt;/span&gt;&lt;span class="nf"&gt;map&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;c&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="nf"&gt;formatAccessibilityTree&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;c&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;depth&lt;/span&gt; &lt;span class="o"&gt;+&lt;/span&gt; &lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;)).&lt;/span&gt;&lt;span class="nf"&gt;join&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;''&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;

    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;indent&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;  &lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;repeat&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;depth&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
    &lt;span class="kd"&gt;let&lt;/span&gt; &lt;span class="nx"&gt;result&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="s2"&gt;`&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;indent&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;[&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;role&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;] &lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;name&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="dl"&gt;''&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;`&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="nx"&gt;result&lt;/span&gt; &lt;span class="o"&gt;+=&lt;/span&gt; &lt;span class="s2"&gt;` value="&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;"`&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="nx"&gt;result&lt;/span&gt; &lt;span class="o"&gt;+=&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="se"&gt;\n&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="k"&gt;for &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;child&lt;/span&gt; &lt;span class="k"&gt;of&lt;/span&gt; &lt;span class="nx"&gt;node&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;children&lt;/span&gt; &lt;span class="o"&gt;||&lt;/span&gt; &lt;span class="p"&gt;[])&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="nx"&gt;result&lt;/span&gt; &lt;span class="o"&gt;+=&lt;/span&gt; &lt;span class="nf"&gt;formatAccessibilityTree&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;child&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;options&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;depth&lt;/span&gt; &lt;span class="o"&gt;+&lt;/span&gt; &lt;span class="mi"&gt;1&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nx"&gt;result&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  LLM Action Planning
&lt;/h3&gt;

&lt;p&gt;Send the page structure to the LLM with the task description. The LLM returns a sequence of actions:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;planActions&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;pageStructure&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;task&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="nx"&gt;Action&lt;/span&gt;&lt;span class="p"&gt;[]&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;response&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;llm&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;generate&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
        &lt;span class="na"&gt;model&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;gpt-4o-mini&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="c1"&gt;// Fast model for action planning&lt;/span&gt;
        &lt;span class="na"&gt;messages&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;
            &lt;span class="p"&gt;{&lt;/span&gt;
                &lt;span class="na"&gt;role&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;system&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="na"&gt;content&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;`You are a browser automation assistant. Given a page structure and a task,
                return a JSON array of actions to accomplish the task.
                Available actions: click(selector), type(selector, text), select(selector, value),
                wait(ms), extract(selector).
                Use the element text/labels to identify targets, not CSS selectors.`&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="p"&gt;},&lt;/span&gt;
            &lt;span class="p"&gt;{&lt;/span&gt;
                &lt;span class="na"&gt;role&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;user&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
                &lt;span class="na"&gt;content&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="s2"&gt;`Page structure:\n&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;pageStructure&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;\n\nTask: &lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;task&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;`&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
            &lt;span class="p"&gt;},&lt;/span&gt;
        &lt;span class="p"&gt;],&lt;/span&gt;
        &lt;span class="na"&gt;responseFormat&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;json&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="p"&gt;});&lt;/span&gt;

    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nx"&gt;JSON&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;parse&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;response&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;text&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="c1"&gt;// Example task: "Fill in the contact form with name Sara Mustermann and email sara.mustermann@beispiel.de"&lt;/span&gt;
&lt;span class="c1"&gt;// LLM returns:&lt;/span&gt;
&lt;span class="c1"&gt;// [&lt;/span&gt;
&lt;span class="c1"&gt;//   { "action": "type", "target": "Name input field", "value": "Sara Mustermann" },&lt;/span&gt;
&lt;span class="c1"&gt;//   { "action": "type", "target": "Email input field", "value": "sara.mustermann@beispiel.de" },&lt;/span&gt;
&lt;span class="c1"&gt;//   { "action": "click", "target": "Submit button" }&lt;/span&gt;
&lt;span class="c1"&gt;// ]&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h3&gt;
  
  
  Resolving LLM Actions to Playwright Commands
&lt;/h3&gt;

&lt;p&gt;The LLM returns human-readable targets ("Name input field"). A resolver maps them to Playwright selectors:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;resolveAndExecute&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Page&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;actions&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Action&lt;/span&gt;&lt;span class="p"&gt;[]):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="k"&gt;void&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="k"&gt;for &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;action&lt;/span&gt; &lt;span class="k"&gt;of&lt;/span&gt; &lt;span class="nx"&gt;actions&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="c1"&gt;// Find the element matching the LLM's description&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;element&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nf"&gt;findElementByDescription&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;target&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;

        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="o"&gt;!&lt;/span&gt;&lt;span class="nx"&gt;element&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;throw&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;ActionError&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;`Could not find element: &lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;target&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;`&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;

        &lt;span class="k"&gt;switch &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;case&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;click&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;element&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;click&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
                &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;waitForLoadState&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;networkidle&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
                &lt;span class="k"&gt;break&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
            &lt;span class="k"&gt;case&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;type&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;element&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;fill&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
                &lt;span class="k"&gt;break&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
            &lt;span class="k"&gt;case&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;select&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;element&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;selectOption&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
                &lt;span class="k"&gt;break&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
            &lt;span class="k"&gt;case&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;wait&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;waitForTimeout&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
                &lt;span class="k"&gt;break&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
            &lt;span class="k"&gt;case&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;extract&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt;
                &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;text&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;element&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;textContent&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
                &lt;span class="nx"&gt;results&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;push&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt; &lt;span class="na"&gt;field&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;action&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;target&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="na"&gt;value&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;text&lt;/span&gt; &lt;span class="p"&gt;});&lt;/span&gt;
                &lt;span class="k"&gt;break&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;

&lt;span class="k"&gt;async&lt;/span&gt; &lt;span class="kd"&gt;function&lt;/span&gt; &lt;span class="nf"&gt;findElementByDescription&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Page&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;):&lt;/span&gt; &lt;span class="nb"&gt;Promise&lt;/span&gt;&lt;span class="o"&gt;&amp;lt;&lt;/span&gt;&lt;span class="nx"&gt;ElementHandle&lt;/span&gt; &lt;span class="o"&gt;|&lt;/span&gt; &lt;span class="kc"&gt;null&lt;/span&gt;&lt;span class="o"&gt;&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="c1"&gt;// Try multiple strategies to find the element&lt;/span&gt;
    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;strategies&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;
        &lt;span class="c1"&gt;// By aria-label&lt;/span&gt;
        &lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;$&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;`[aria-label*="&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;" i]`&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
        &lt;span class="c1"&gt;// By placeholder&lt;/span&gt;
        &lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;$&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;`[placeholder*="&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;" i]`&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
        &lt;span class="c1"&gt;// By visible text&lt;/span&gt;
        &lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;$&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;`text=&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;`&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
        &lt;span class="c1"&gt;// By label association&lt;/span&gt;
        &lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;$&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="s2"&gt;`label:has-text("&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;") + input, label:has-text("&lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;") input`&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
        &lt;span class="c1"&gt;// By role and name&lt;/span&gt;
        &lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getByRole&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;textbox&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;RegExp&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;i&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;}).&lt;/span&gt;&lt;span class="nf"&gt;first&lt;/span&gt;&lt;span class="p"&gt;().&lt;/span&gt;&lt;span class="nf"&gt;elementHandle&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt;
        &lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;getByRole&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;button&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;name&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;RegExp&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;description&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;i&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;}).&lt;/span&gt;&lt;span class="nf"&gt;first&lt;/span&gt;&lt;span class="p"&gt;().&lt;/span&gt;&lt;span class="nf"&gt;elementHandle&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt;
    &lt;span class="p"&gt;];&lt;/span&gt;

    &lt;span class="k"&gt;for &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;strategy&lt;/span&gt; &lt;span class="k"&gt;of&lt;/span&gt; &lt;span class="nx"&gt;strategies&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="k"&gt;try&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;element&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nf"&gt;strategy&lt;/span&gt;&lt;span class="p"&gt;();&lt;/span&gt;
            &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;element&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nx"&gt;element&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;catch&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
            &lt;span class="k"&gt;continue&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;

    &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="kc"&gt;null&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
&lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;h2&gt;
  
  
  Anti-Detection Basics
&lt;/h2&gt;

&lt;p&gt;Some websites detect and block headless browsers. Basic countermeasures:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;&lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;context&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;browser&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;newContext&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
    &lt;span class="c1"&gt;// Randomize viewport&lt;/span&gt;
    &lt;span class="na"&gt;viewport&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="na"&gt;width&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;1280&lt;/span&gt; &lt;span class="o"&gt;+&lt;/span&gt; &lt;span class="nb"&gt;Math&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;floor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nb"&gt;Math&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;random&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;*&lt;/span&gt; &lt;span class="mi"&gt;200&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
        &lt;span class="na"&gt;height&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;720&lt;/span&gt; &lt;span class="o"&gt;+&lt;/span&gt; &lt;span class="nb"&gt;Math&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;floor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nb"&gt;Math&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;random&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;*&lt;/span&gt; &lt;span class="mi"&gt;100&lt;/span&gt;&lt;span class="p"&gt;),&lt;/span&gt;
    &lt;span class="p"&gt;},&lt;/span&gt;

    &lt;span class="c1"&gt;// Rotate user agents&lt;/span&gt;
    &lt;span class="na"&gt;userAgent&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nf"&gt;getRandomUserAgent&lt;/span&gt;&lt;span class="p"&gt;(),&lt;/span&gt;

    &lt;span class="c1"&gt;// Set realistic locale and timezone&lt;/span&gt;
    &lt;span class="na"&gt;locale&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;de-DE&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
    &lt;span class="na"&gt;timezoneId&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;Europe/Berlin&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;

    &lt;span class="c1"&gt;// Realistic geolocation&lt;/span&gt;
    &lt;span class="na"&gt;geolocation&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;latitude&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mf"&gt;48.1351&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="na"&gt;longitude&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mf"&gt;11.5820&lt;/span&gt; &lt;span class="p"&gt;},&lt;/span&gt;
    &lt;span class="na"&gt;permissions&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;geolocation&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
&lt;span class="p"&gt;});&lt;/span&gt;

&lt;span class="c1"&gt;// Override navigator.webdriver (headless detection)&lt;/span&gt;
&lt;span class="k"&gt;await&lt;/span&gt; &lt;span class="nx"&gt;page&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;addInitScript&lt;/span&gt;&lt;span class="p"&gt;(()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
    &lt;span class="nb"&gt;Object&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nf"&gt;defineProperty&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nb"&gt;navigator&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;webdriver&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="na"&gt;get&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="o"&gt;=&amp;gt;&lt;/span&gt; &lt;span class="kc"&gt;undefined&lt;/span&gt; &lt;span class="p"&gt;});&lt;/span&gt;
&lt;span class="p"&gt;});&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Note: anti-detection is an arms race. For sites with sophisticated bot detection (Cloudflare, Akamai), self-hosted Playwright will eventually be detected. This is where paid services like BrowserBase add value: they invest continuously in anti-detection. For most business automation tasks (internal tools, partner portals, public data), basic anti-detection is sufficient.&lt;/p&gt;

&lt;h2&gt;
  
  
  When Paid Tools ARE Worth It
&lt;/h2&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Scenario&lt;/th&gt;
&lt;th&gt;Self-Hosted&lt;/th&gt;
&lt;th&gt;Paid Service&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;Internal tool automation&lt;/td&gt;
&lt;td&gt;Best choice (no anti-detection needed)&lt;/td&gt;
&lt;td&gt;Overkill&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Public data extraction (simple)&lt;/td&gt;
&lt;td&gt;Good (basic anti-detection works)&lt;/td&gt;
&lt;td&gt;Unnecessary&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Sites with bot detection&lt;/td&gt;
&lt;td&gt;Possible but constant maintenance&lt;/td&gt;
&lt;td&gt;Worth it (they handle anti-detection)&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;High-volume scraping (10K+ pages/day)&lt;/td&gt;
&lt;td&gt;Complex (proxy rotation, IP management)&lt;/td&gt;
&lt;td&gt;Worth it (managed infrastructure)&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Regulated data (GDPR, compliance)&lt;/td&gt;
&lt;td&gt;Better (data stays on your infrastructure)&lt;/td&gt;
&lt;td&gt;Risk (data goes through third party)&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;One-time migration&lt;/td&gt;
&lt;td&gt;Good (temporary workload)&lt;/td&gt;
&lt;td&gt;Unnecessary cost&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;p&gt;The decision framework: if you're automating internal workflows or processing public data from sites without aggressive bot detection, self-host. If you're doing high-volume extraction from sites with Cloudflare-level protection, pay for a service that handles anti-detection as their core business.&lt;/p&gt;

&lt;h2&gt;
  
  
  Cost Comparison
&lt;/h2&gt;

&lt;div class="table-wrapper-paragraph"&gt;&lt;table&gt;
&lt;thead&gt;
&lt;tr&gt;
&lt;th&gt;Component&lt;/th&gt;
&lt;th&gt;Self-Hosted (monthly)&lt;/th&gt;
&lt;th&gt;BrowserBase (monthly)&lt;/th&gt;
&lt;/tr&gt;
&lt;/thead&gt;
&lt;tbody&gt;
&lt;tr&gt;
&lt;td&gt;Compute (5 instances)&lt;/td&gt;
&lt;td&gt;$50-100 (container/VPS)&lt;/td&gt;
&lt;td&gt;N/A&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;LLM calls (action planning)&lt;/td&gt;
&lt;td&gt;$20-50 (GPT-4o-mini)&lt;/td&gt;
&lt;td&gt;N/A&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;BrowserBase sessions&lt;/td&gt;
&lt;td&gt;N/A&lt;/td&gt;
&lt;td&gt;$500-2,000&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Proxy service (if needed)&lt;/td&gt;
&lt;td&gt;$50-200&lt;/td&gt;
&lt;td&gt;Included&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;Maintenance&lt;/td&gt;
&lt;td&gt;2-4 hours/month&lt;/td&gt;
&lt;td&gt;None&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Total (1,000 pages/day)&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;strong&gt;$120-350/month&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;strong&gt;$500-2,000/month&lt;/strong&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;
&lt;td&gt;&lt;strong&gt;Total (10,000 pages/day)&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;strong&gt;$300-800/month&lt;/strong&gt;&lt;/td&gt;
&lt;td&gt;&lt;strong&gt;$3,000-10,000/month&lt;/strong&gt;&lt;/td&gt;
&lt;/tr&gt;
&lt;/tbody&gt;
&lt;/table&gt;&lt;/div&gt;

&lt;p&gt;Self-hosting is 3-10x cheaper at scale. The trade-off is maintenance time and anti-detection capability.&lt;/p&gt;

&lt;h2&gt;
  
  
  Common Pitfalls
&lt;/h2&gt;

&lt;ol&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;No instance pooling.&lt;/strong&gt; Launching a new browser per task wastes 1-3 seconds on cold start and 200-400MB of RAM. Pool and reuse instances.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Hardcoded CSS selectors.&lt;/strong&gt; Pages change their DOM structure regularly. LLM-based element identification is more resilient than hardcoded selectors.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;No session persistence.&lt;/strong&gt; Multi-step workflows that require login fail when the session state is lost between steps.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Ignoring anti-detection entirely.&lt;/strong&gt; Even basic measures (random viewport, user agent rotation, webdriver override) prevent detection on most sites.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Using a large model for action planning.&lt;/strong&gt; GPT-4o-mini or Claude Haiku are fast enough for page understanding. A large model adds latency without better accuracy for this task.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;No timeout on page loads.&lt;/strong&gt; Some pages load indefinitely (infinite scrolling, slow third-party scripts). Set a navigation timeout and handle it.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Running in production without monitoring.&lt;/strong&gt; Track success rate, average execution time, and error types per workflow. Alert when success rate drops.&lt;/p&gt;&lt;/li&gt;
&lt;/ol&gt;

&lt;h2&gt;
  
  
  Key Takeaways
&lt;/h2&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Self-hosted Playwright + LLM handles 90% of browser automation use cases.&lt;/strong&gt; For internal tools, partner portals, and public data without aggressive bot detection, this is the right approach.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Instance pooling is essential.&lt;/strong&gt; Reuse browser instances across tasks. Cold starts and memory allocation are the biggest performance bottleneck.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;LLM page understanding replaces brittle selectors.&lt;/strong&gt; Send the accessibility tree to a fast model. Let it decide which elements to interact with. More resilient to page changes than hardcoded CSS selectors.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Paid services earn their cost on anti-detection.&lt;/strong&gt; If your target sites have Cloudflare or similar protection, BrowserBase invests continuously in bypassing it. That's their core business. Don't try to compete.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;&lt;strong&gt;Self-hosting is 3-10x cheaper at scale.&lt;/strong&gt; But you pay in maintenance time and anti-detection limitations. Make the trade-off consciously.&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;FIND MORE: &lt;a href="https://oronts.com/en/guides/browser-automation-ai-without-paid-tools" rel="noopener noreferrer"&gt;https://oronts.com/en/guides/browser-automation-ai-without-paid-tools&lt;/a&gt;&lt;/p&gt;

</description>
      <category>ai</category>
      <category>automation</category>
      <category>playwright</category>
      <category>mcp</category>
    </item>
    <item>
      <title>CodeRanedeer: An AI-Powered Programming Assistant</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Mon, 08 May 2023 19:14:30 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/coderanedeer-an-ai-powered-programming-assistant-51gb</link>
      <guid>https://dev.to/refaatalktifan/coderanedeer-an-ai-powered-programming-assistant-51gb</guid>
      <description>&lt;h3&gt;
  
  
  Enhance Your Coding Experience with CodeRanedeer: An AI-Powered Programming Assistant (GPT 4 prompt)
&lt;/h3&gt;

&lt;p&gt;&lt;a href="https://refaat-alktifan.github.io/CodeRanedeer/" rel="noopener noreferrer"&gt;&lt;strong&gt;AI Code Buddy - CodeRanedeer&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;Discover how CodeRanedeer, an AI-powered language model (GPT 4 prompt), can help you write, fix, review, and explain code with personalized learning experiences and interaction styles.&lt;/p&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fyaw2zl2l77hnhwmafdjc.png" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2Fyaw2zl2l77hnhwmafdjc.png" alt="CodeRanedeer: An AI-Powered Programming Assistant" width="512" height="512"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;h2&gt;
  
  
  Introduction:
&lt;/h2&gt;

&lt;p&gt;Whether you’re a beginner or an experienced programmer, having a helping hand while writing, fixing, or reviewing code can make a significant difference in your productivity. CodeRanedeer, an AI-powered programming assistant developed by Refaat Al Ktifan, is designed to cater to your coding needs with personalized learning experiences and interaction styles. This blog post will introduce CodeRanedeer, walk you through its features, and provide examples to showcase its capabilities. Check out the GitHub repository here: &lt;a href="https://github.com/Refaat-alktifan/CodeRanedeer" rel="noopener noreferrer"&gt;https://github.com/Refaat-alktifan/CodeRanedeer&lt;/a&gt;&lt;/p&gt;

&lt;h2&gt;
  
  
  Section 1:
&lt;/h2&gt;

&lt;p&gt;Overview of CodeRanedeer CodeRanedeer is an AI language model that assists with various code-oriented tasks such as writing, fixing, reviewing, and explaining programming code. It can also serve as a pair programming buddy, enhancing your coding experience through collaboration. CodeRanedeer offers personalization options to cater to individual learning preferences and interaction styles.&lt;/p&gt;

&lt;h2&gt;
  
  
  Section 2:
&lt;/h2&gt;

&lt;p&gt;Personalization Features CodeRanedeer provides personalized learning experiences and interaction styles based on user preferences. It offers the following personalization options:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;&lt;p&gt;Depth: Determines the level of detail in explanations and assistance, ranging from basic concepts to advanced techniques.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Interaction Styles: Specifies the AI’s role in the interaction, such as providing guidance or collaborating as a pair programming buddy.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Explanation Styles: Defines how the AI presents information, catering to different levels of programming expertise and learning preferences.&lt;/p&gt;&lt;/li&gt;
&lt;/ol&gt;

&lt;h2&gt;
  
  
  Section 3:
&lt;/h2&gt;

&lt;p&gt;Commands and Configuration CodeRanedeer features a range of commands to help you perform code-oriented tasks. These include:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;/write_code: Write code based on user’s specifications.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;/fix_code: Identify and fix issues in the provided code.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;/review_code: Review the provided code and offer suggestions for improvement.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;/explain_code: Explain the provided code or concepts to the user.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;/pair_program: Engage in pair programming with the user.&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;You can also configure CodeRanedeer according to your preferences, including depth, interaction style, explanation style, and language.&lt;/p&gt;

&lt;h2&gt;
  
  
  Section 4:
&lt;/h2&gt;

&lt;p&gt;Example Use Cases Here are some examples showcasing CodeRanedeer’s capabilities:&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;&lt;p&gt;Writing code: CodeRanedeer can write a Python function to calculate the factorial of a given number.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Reviewing code: CodeRanedeer can review your Python code, offering suggestions for improvement or optimization.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Fixing code: CodeRanedeer can identify issues in your JavaScript code and provide fixes, ensuring your code is working correctly.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Explaining code: CodeRanedeer can break down and explain Java code, making it easier to understand the logic and flow of the program.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Pair programming: CodeRanedeer can help you create a Python script to find the greatest common divisor (GCD) of two numbers, engaging in pair programming to enhance your coding experience.&lt;/p&gt;&lt;/li&gt;
&lt;/ol&gt;

&lt;h2&gt;
  
  
  Conclusion:
&lt;/h2&gt;

&lt;p&gt;CodeRanedeer is an invaluable AI-powered programming assistant (GPT 4 prompt) that can help you with various code-oriented tasks while catering to your learning preferences and interaction styles. With CodeRanedeer, you can improve your coding skills, enhance your understanding of programming concepts, and boost your productivity. Don’t forget to visit the GitHub repository to explore CodeRanedeer further: &lt;a href="https://github.com/Refaat-alktifan/CodeRanedeer" rel="noopener noreferrer"&gt;https://github.com/Refaat-alktifan/CodeRanedeer&lt;/a&gt;&lt;br&gt;
&lt;a href="https://refaat-alktifan.github.io/CodeRanedeer/" rel="noopener noreferrer"&gt;&lt;strong&gt;AI Code Buddy - CodeRanedeer&lt;/strong&gt;&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;Keywords: CodeRanedeer, AI-powered, programming assistant, personalized learning, chatgpt, gpt4, ai, free ai&lt;/p&gt;

</description>
      <category>ai</category>
      <category>chatgpt</category>
      <category>gpt4</category>
      <category>programming</category>
    </item>
    <item>
      <title>0–7 NestJS Hunter: Slaying Complexity in Node.js with TypeScript.</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sun, 07 May 2023 16:05:04 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/0-7-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-4i38</link>
      <guid>https://dev.to/refaatalktifan/0-7-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-4i38</guid>
      <description>&lt;h2&gt;
  
  
  Pipes are an essential feature of NestJS, used for handling data transformation and validation in a clean and maintainable way. Pipes are classes that implement the PipeTransform interface, which requires a single method: transform(). This method takes an input value and returns a transformed value or throws an exception if the value is invalid.
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" width="800" height="516"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;There are two primary use cases for pipes in NestJS:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Validation: Pipes can validate incoming data, ensuring it meets specific requirements before it’s passed to a controller method. If the data is invalid, the pipe can throw an exception, which NestJS will convert into an appropriate HTTP error response.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;For example, you can use the built-in ValidationPipe to automatically validate incoming data against a class-validator schema:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;Controller&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Post&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Body&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;UsePipes&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;ValidationPipe&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;CreateCatDto&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;./dto/create-cat.dto&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Controller&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;cats&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="k"&gt;export&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;CatsController&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Post&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
      &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;UsePipes&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;ValidationPipe&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
      &lt;span class="nf"&gt;create&lt;/span&gt;&lt;span class="p"&gt;(@&lt;/span&gt;&lt;span class="nd"&gt;Body&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="nx"&gt;createCatDto&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;CreateCatDto&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="c1"&gt;// Implementation of the create method&lt;/span&gt;
      &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;ul&gt;
&lt;li&gt;Data Transformation: Pipes can transform incoming data, allowing you to modify or normalize it before it reaches a controller method. This is useful for cases like converting strings to numbers or formatting date strings.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;For instance, you can create a custom pipe to parse a string into a number:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;PipeTransform&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Injectable&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;BadRequestException&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Injectable&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
    &lt;span class="k"&gt;export&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;ParseIntPipe&lt;/span&gt; &lt;span class="k"&gt;implements&lt;/span&gt; &lt;span class="nx"&gt;PipeTransform&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="nf"&gt;transform&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;val&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="nf"&gt;parseInt&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;value&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="mi"&gt;10&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="k"&gt;if &lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nf"&gt;isNaN&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="nx"&gt;val&lt;/span&gt;&lt;span class="p"&gt;))&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
          &lt;span class="k"&gt;throw&lt;/span&gt; &lt;span class="k"&gt;new&lt;/span&gt; &lt;span class="nc"&gt;BadRequestException&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;Validation failed&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;);&lt;/span&gt;
        &lt;span class="p"&gt;}&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="nx"&gt;val&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
      &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;To use this custom pipe, apply it to a controller method with the @UsePipes() decorator:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;Controller&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Get&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Param&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;UsePipes&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;ParseIntPipe&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;./parse-int.pipe&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Controller&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;cats&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="k"&gt;export&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;CatsController&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Get&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;:id&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
      &lt;span class="nf"&gt;findOne&lt;/span&gt;&lt;span class="p"&gt;(@&lt;/span&gt;&lt;span class="nd"&gt;Param&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;id&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;ParseIntPipe&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="nx"&gt;id&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;number&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="c1"&gt;// Implementation of the findOne method&lt;/span&gt;
      &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;Pipes help maintain a clean and organized codebase by handling validation and transformation concerns separately from the core business logic.&lt;/p&gt;

&lt;p&gt;Next, let’s explore the concept of interceptors in NestJS. How do interceptors work, and what are some common use cases for them in a NestJS application?&lt;/p&gt;

&lt;p&gt;to be continued&lt;/p&gt;

</description>
      <category>webdev</category>
      <category>javascript</category>
      <category>tutorial</category>
      <category>programming</category>
    </item>
    <item>
      <title>0–6 NestJS Hunter: Slaying Complexity in Node.js with TypeScript.</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sun, 07 May 2023 16:02:35 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/0-6-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-1nom</link>
      <guid>https://dev.to/refaatalktifan/0-6-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-1nom</guid>
      <description>&lt;h2&gt;
  
  
  Dependency Injection (DI) is a design pattern used in NestJS to manage dependencies between classes, promoting decoupling and making it easier to test and maintain the code. In NestJS, the DI system is built around the concept of providers and tokens.
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" width="800" height="516"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Providers: A provider is a class, value, or factory function responsible for creating an object that can be injected into other classes. Providers are typically registered in the providers array of a module. Here's an example of a provider class:
&lt;/li&gt;
&lt;/ul&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;Injectable&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Injectable&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
    &lt;span class="k"&gt;export&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;CatsService&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="c1"&gt;// Implementation of the service&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Tokens: Tokens are unique identifiers used by NestJS to locate providers. By default, a class’s token is the class itself. When a class needs a dependency, it requests it from the DI system using a token.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Injecting Dependencies: To inject a dependency, you can use the @Inject() decorator in the constructor of a class. The DI system will then resolve the dependency and provide an instance of the requested class. Here's an example:&lt;br&gt;
&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;Injectable&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Inject&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;CatsService&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;./cats.service&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Injectable&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
    &lt;span class="k"&gt;export&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;AppService&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="nf"&gt;constructor&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="k"&gt;private&lt;/span&gt; &lt;span class="k"&gt;readonly&lt;/span&gt; &lt;span class="nx"&gt;catsService&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;CatsService&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt; &lt;span class="p"&gt;{}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;In this example, the AppService class requests an instance of CatsService in its constructor. The DI system locates the CatsService provider, creates an instance, and injects it into the AppService class.&lt;/p&gt;

&lt;p&gt;Dependency Injection in NestJS provides the following benefits:&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;&lt;p&gt;Decoupling: DI promotes loose coupling between classes by allowing them to depend on abstractions rather than concrete implementations. This makes it easier to modify or replace parts of the application without affecting other components.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Testing: DI makes it simpler to test classes by allowing you to replace dependencies with mock implementations during testing.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Reusability: By managing dependencies centrally, DI encourages the reuse of providers across multiple parts of the application.&lt;/p&gt;&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;Now that you understand Dependency Injection in NestJS, let’s discuss the role of pipes and their use cases. How can pipes help with validation and data transformation in a NestJS application?&lt;/p&gt;

&lt;p&gt;to be continued&lt;/p&gt;

</description>
      <category>webdev</category>
      <category>javascript</category>
      <category>beginners</category>
      <category>programming</category>
    </item>
    <item>
      <title>0–5 NestJS Hunter: Slaying Complexity in Node.js with TypeScript.</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sun, 07 May 2023 15:56:12 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/0-5-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-1ao9</link>
      <guid>https://dev.to/refaatalktifan/0-5-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-1ao9</guid>
      <description>&lt;h2&gt;
  
  
  Modules and decorators are fundamental concepts in NestJS that contribute to its modular architecture, helping you create well-structured and maintainable applications.
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" width="800" height="516"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;ul&gt;
&lt;li&gt;Modules: In NestJS, a module is a class annotated with the @Module() decorator, responsible for organizing application components such as controllers, providers, and other modules. By grouping related components together, modules make it easier to manage large applications and promote code reusability.&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;A typical NestJS module looks like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;Module&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;CatsController&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;./cats.controller&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;CatsService&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;./cats.service&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Module&lt;/span&gt;&lt;span class="p"&gt;({&lt;/span&gt;
      &lt;span class="na"&gt;controllers&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="nx"&gt;CatsController&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
      &lt;span class="na"&gt;providers&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="p"&gt;[&lt;/span&gt;&lt;span class="nx"&gt;CatsService&lt;/span&gt;&lt;span class="p"&gt;],&lt;/span&gt;
    &lt;span class="p"&gt;})&lt;/span&gt;
    &lt;span class="k"&gt;export&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;CatsModule&lt;/span&gt; &lt;span class="p"&gt;{}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;ul&gt;
&lt;li&gt;Decorators: Decorators are a TypeScript feature that allows you to add metadata to classes, properties, and methods. In NestJS, decorators are used extensively to enhance classes and provide additional information to the framework. Some common decorators in NestJS include @Controller(), &lt;a class="mentioned-user" href="https://dev.to/get"&gt;@get&lt;/a&gt;(), &lt;a class="mentioned-user" href="https://dev.to/post"&gt;@post&lt;/a&gt;(), and @Inject().&lt;/li&gt;
&lt;/ul&gt;

&lt;p&gt;For instance, a basic NestJS controller using decorators could look like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="k"&gt;import&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt; &lt;span class="nx"&gt;Controller&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt; &lt;span class="nx"&gt;Get&lt;/span&gt; &lt;span class="p"&gt;}&lt;/span&gt; &lt;span class="k"&gt;from&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;@nestjs/common&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;

    &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Controller&lt;/span&gt;&lt;span class="p"&gt;(&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;cats&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;)&lt;/span&gt;
    &lt;span class="k"&gt;export&lt;/span&gt; &lt;span class="kd"&gt;class&lt;/span&gt; &lt;span class="nc"&gt;CatsController&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="p"&gt;@&lt;/span&gt;&lt;span class="nd"&gt;Get&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt;
      &lt;span class="nf"&gt;findAll&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="s1"&gt;This action returns all cats.&lt;/span&gt;&lt;span class="dl"&gt;'&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
      &lt;span class="p"&gt;}&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;The @Controller('cats') decorator marks the CatsController class as a controller and associates it with the 'cats' route. The &lt;a class="mentioned-user" href="https://dev.to/get"&gt;@get&lt;/a&gt;() decorator is applied to the findAll method, indicating that it should handle HTTP GET requests.&lt;/p&gt;

&lt;p&gt;By leveraging modules and decorators, NestJS enforces a clean, modular structure for your application, making it easier to manage, extend, and maintain.&lt;/p&gt;

&lt;p&gt;Now, let’s explore a crucial aspect of NestJS: dependency injection. Can you explain how dependency injection works in NestJS and how it helps with decoupling and testing?&lt;/p&gt;

&lt;p&gt;to be continued&lt;/p&gt;

</description>
      <category>webdev</category>
      <category>javascript</category>
      <category>beginners</category>
      <category>programming</category>
    </item>
    <item>
      <title>0–4 NestJS Hunter: Slaying Complexity in Node.js with TypeScript.</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sun, 07 May 2023 15:54:46 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/0-4-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-akg</link>
      <guid>https://dev.to/refaatalktifan/0-4-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-akg</guid>
      <description>&lt;h2&gt;
  
  
  Interfaces in TypeScript are a powerful way to define contracts for the shape of objects, allowing you to enforce specific structures for objects and create reusable type definitions. They can also be used for type checking and autocompletion support in code editors.
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" width="800" height="516"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;Here’s an example of an interface in TypeScript:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="kr"&gt;interface&lt;/span&gt; &lt;span class="nx"&gt;Person&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="nl"&gt;firstName&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
      &lt;span class="nl"&gt;lastName&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
      &lt;span class="nl"&gt;age&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="kr"&gt;number&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
      &lt;span class="nf"&gt;greet&lt;/span&gt;&lt;span class="p"&gt;():&lt;/span&gt; &lt;span class="kr"&gt;string&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
    &lt;span class="p"&gt;}&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;This interface defines a Person object with firstName, lastName, and age properties, as well as a greet method. You can use the interface as a type for an object like this:&lt;br&gt;
&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight typescript"&gt;&lt;code&gt;    &lt;span class="kd"&gt;const&lt;/span&gt; &lt;span class="nx"&gt;john&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="nx"&gt;Person&lt;/span&gt; &lt;span class="o"&gt;=&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
      &lt;span class="na"&gt;firstName&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;"&lt;/span&gt;&lt;span class="s2"&gt;John&lt;/span&gt;&lt;span class="dl"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
      &lt;span class="na"&gt;lastName&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="dl"&gt;"&lt;/span&gt;&lt;span class="s2"&gt;Doe&lt;/span&gt;&lt;span class="dl"&gt;"&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
      &lt;span class="na"&gt;age&lt;/span&gt;&lt;span class="p"&gt;:&lt;/span&gt; &lt;span class="mi"&gt;30&lt;/span&gt;&lt;span class="p"&gt;,&lt;/span&gt;
      &lt;span class="nf"&gt;greet&lt;/span&gt;&lt;span class="p"&gt;()&lt;/span&gt; &lt;span class="p"&gt;{&lt;/span&gt;
        &lt;span class="k"&gt;return&lt;/span&gt; &lt;span class="s2"&gt;`Hello, my name is &lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;firstName&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt; &lt;/span&gt;&lt;span class="p"&gt;${&lt;/span&gt;&lt;span class="k"&gt;this&lt;/span&gt;&lt;span class="p"&gt;.&lt;/span&gt;&lt;span class="nx"&gt;lastName&lt;/span&gt;&lt;span class="p"&gt;}&lt;/span&gt;&lt;span class="s2"&gt;.`&lt;/span&gt;&lt;span class="p"&gt;;&lt;/span&gt;
      &lt;span class="p"&gt;},&lt;/span&gt;
    &lt;span class="p"&gt;};&lt;/span&gt;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;



&lt;p&gt;If you try to create an object that doesn’t match the Person interface, TypeScript will throw a type error during compilation.&lt;/p&gt;

&lt;p&gt;Now let’s shift our focus to NestJS. Can you explain the importance of modules and decorators in NestJS and how they contribute to the framework’s modular architecture?&lt;/p&gt;

&lt;p&gt;to be continued&lt;/p&gt;

</description>
      <category>webdev</category>
      <category>javascript</category>
      <category>beginners</category>
      <category>programming</category>
    </item>
    <item>
      <title>0–3 NestJS Hunter: Slaying Complexity in Node.js with TypeScript.</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sat, 06 May 2023 15:56:26 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/0-3-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-461k</link>
      <guid>https://dev.to/refaatalktifan/0-3-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-461k</guid>
      <description>&lt;h2&gt;
  
  
  Static typing and dynamic typing are two approaches to handling data types in programming languages.
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" width="800" height="516"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;In static typing, the data type of a variable is known at compile time, meaning that the type is explicitly specified or inferred when the code is written. This allows for type checking before the code is executed, which can help catch potential errors early and improve code reliability. Languages with static typing include TypeScript, Java, and C++.&lt;/p&gt;

&lt;p&gt;In dynamic typing, the data type of a variable is determined at runtime, meaning that it’s determined when the code is executed. Variables can change types during the execution of a program, which can make the code more flexible but also more prone to errors. Languages with dynamic typing include JavaScript, Python, and Ruby.&lt;/p&gt;

&lt;p&gt;Now that we’ve briefly discussed static typing, let’s delve into TypeScript basics. TypeScript introduces static typing to JavaScript, providing several data types such as number, string, boolean, null, and undefined. In addition, TypeScript has more advanced types like any, unknown, never, tuple, and enum.&lt;/p&gt;

&lt;p&gt;For instance, declaring a variable with a specific type in TypeScript looks like this:&lt;/p&gt;

&lt;div class="highlight js-code-highlight"&gt;
&lt;pre class="highlight plaintext"&gt;&lt;code&gt;let age: number = 25;
&lt;/code&gt;&lt;/pre&gt;

&lt;/div&gt;

&lt;p&gt;If you try to assign a non-number value to the age variable, TypeScript will throw a type error during compilation.&lt;/p&gt;

&lt;p&gt;Are you familiar with interfaces in TypeScript? If so, can you provide an example?&lt;/p&gt;

&lt;p&gt;to be continued&lt;/p&gt;

</description>
      <category>webdev</category>
      <category>javascript</category>
      <category>beginners</category>
      <category>programming</category>
    </item>
    <item>
      <title>0–2 NestJS Hunter: Slaying Complexity in Node.js with TypeScript.</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sat, 06 May 2023 15:55:24 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/0-2-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-714</link>
      <guid>https://dev.to/refaatalktifan/0-2-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-714</guid>
      <description>&lt;h2&gt;
  
  
  Using TypeScript, NestJS, and Node.js together is beneficial for modern web development for several reasons:
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fcdn-images-1.medium.com%2Fmax%2F2000%2F1%2AoIEU9gn7RTLkMgUILN4bLQ.jpeg" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fcdn-images-1.medium.com%2Fmax%2F2000%2F1%2AoIEU9gn7RTLkMgUILN4bLQ.jpeg" width="800" height="516"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;ol&gt;
&lt;li&gt;&lt;p&gt;Type Safety: TypeScript’s static typing helps catch potential errors during development, leading to more reliable and maintainable code. It can also enhance the development experience with better autocompletion and documentation support in code editors.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Consistent Language: Since Node.js allows you to write server-side code in JavaScript, using TypeScript across both the front-end and back-end of an application enables you to maintain a consistent language throughout the entire development stack.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Modular Architecture: NestJS’s modular approach, inspired by Angular, encourages a well-structured and organized codebase. This makes it easier to manage large applications and promotes code reusability.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Scalability and Performance: Node.js’s event-driven, non-blocking I/O model allows for efficient resource usage and high performance when handling multiple concurrent connections. NestJS enhances this by providing an abstraction layer that simplifies building scalable applications.&lt;/p&gt;&lt;/li&gt;
&lt;li&gt;&lt;p&gt;Growing Ecosystem: The combination of TypeScript, NestJS, and Node.js has a vibrant and growing ecosystem with a vast number of libraries, tools, and resources available to help you build powerful applications more quickly and efficiently.&lt;/p&gt;&lt;/li&gt;
&lt;/ol&gt;

&lt;p&gt;Now that we’ve discussed the benefits of using TypeScript, NestJS, and Node.js together, let’s move on to exploring TypeScript basics. Are you familiar with static typing, and can you explain how it differs from dynamic typing?&lt;/p&gt;

&lt;p&gt;to be continued&lt;/p&gt;

</description>
      <category>webdev</category>
      <category>javascript</category>
      <category>beginners</category>
      <category>programming</category>
    </item>
    <item>
      <title>0–1 NestJS Hunter: Slaying Complexity in Node.js with TypeScript.</title>
      <dc:creator>refaat Al Ktifan</dc:creator>
      <pubDate>Sat, 06 May 2023 15:54:16 +0000</pubDate>
      <link>https://dev.to/refaatalktifan/0-1-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-j1j</link>
      <guid>https://dev.to/refaatalktifan/0-1-nestjs-hunter-slaying-complexity-in-nodejs-with-typescript-j1j</guid>
      <description>&lt;h2&gt;
  
  
  &lt;strong&gt;Let’s start with an introduction to TypeScript, NestJS, and Node.js! 😄&lt;/strong&gt;
&lt;/h2&gt;

&lt;p&gt;&lt;a href="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" class="article-body-image-wrapper"&gt;&lt;img src="https://media2.dev.to/dynamic/image/width=800%2Cheight=%2Cfit=scale-down%2Cgravity=auto%2Cformat=auto/https%3A%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Farticles%2F3xj9ixuc66qvlijvnpqa.jpeg" width="800" height="516"&gt;&lt;/a&gt;&lt;/p&gt;

&lt;p&gt;TypeScript is a superset of JavaScript that adds optional static typing to the language. This means that you can assign types to variables, function parameters, and return values, which helps you catch potential bugs early and improve the overall quality of your code. TypeScript compiles to plain JavaScript, making it compatible with any environment that supports JavaScript.&lt;/p&gt;

&lt;p&gt;NestJS is a popular framework for building efficient, scalable Node.js server-side applications. It uses TypeScript by default and is built with a modular architecture, making it easy to organize your code and create reusable components. NestJS takes inspiration from Angular, bringing familiar concepts like decorators and dependency injection to the Node.js ecosystem.&lt;/p&gt;

&lt;p&gt;Node.js is a runtime environment that allows you to run JavaScript on the server side. It’s built on the V8 JavaScript engine and uses an event-driven, non-blocking I/O model, which makes it lightweight and efficient for building scalable network applications.&lt;/p&gt;

&lt;p&gt;Why do you think using TypeScript, NestJS, and Node.js together is beneficial for modern web development? 🤔&lt;/p&gt;

&lt;p&gt;to be continued&lt;/p&gt;

</description>
      <category>javascript</category>
      <category>node</category>
      <category>nestjs</category>
      <category>programming</category>
    </item>
  </channel>
</rss>
