DEV Community: Jakub Andrzejewski

Fix Web Performance Issues Faster with Modern Web Guidance and Chrome DevTools for AI Agents

Jakub Andrzejewski — Mon, 29 Jun 2026 05:22:27 +0000

Performance optimization has always been one of the hardest parts of web development. You run Lighthouse, record a Performance trace, identify a long task... And then comes the difficult part:

👉 How do you actually fix it?

Traditionally, developers had to spend hours searching documentation, comparing best practices, and figuring out which optimization applied to their situation.

Google is trying to simplify this workflow with two new resources:

Modern Web Guidance
Chrome DevTools for AI Agents

Together, they make it easier for both developers and AI coding assistants to identify and fix common performance issues.

In this article, we'll explore:

What Modern Web Guidance is
What Chrome DevTools for AI Agents does
How they work together
Real-world performance issues they help solve
Best practices for integrating them into your workflow

Let's dive in.

🤔 What Is Modern Web Guidance?

[Modern Web Guidance](https://developer.chrome.com/docs/modern-web-guidance0 is a collection of best practices published by the Chrome team.

Instead of generic advice like:

"Optimize your JavaScript."

It provides practical guidance for modern web applications covering topics such as:

rendering performance
Core Web Vitals
JavaScript optimization
CSS best practices
loading strategies
images and fonts
networking
accessibility

Think of it as a centralized knowledge base for building fast web applications. Instead of searching through dozens of blog posts, you can rely on guidance maintained by the team behind Chrome.

🟢 What Is Chrome DevTools for AI Agents?

Chrome DevTools for AI Agents exposes browser debugging information in a way that AI coding assistants can understand.

Instead of simply analyzing source code, an AI agent can inspect:

Performance traces
Network requests
Console messages
Rendering behavior
Layout shifts
Core Web Vitals

This allows AI assistants to reason about runtime behavior, not just static code.

🟢 How It Works Together

Imagine your application has poor Interaction to Next Paint (INP).

The workflow becomes:

Performance trace
↓
AI Agent analyzes DevTools data
↓
Identifies bottleneck
↓
Matches issue with Modern Web Guidance
↓
Suggests concrete improvements

🟢 Example: Finding a Long JavaScript Task

Suppose DevTools records a long task blocking the main thread. Instead of only showing:

Main thread blocked for 420ms

An AI agent can help explain why the task is expensive, which code caused it, and which optimization patterns apply.

For example; split large computations, lazy load modules, or reduce synchronous work. This dramatically shortens the debugging process.

🟢 Example: Fixing Layout Shifts

Another common issue is Cumulative Layout Shift (CLS). DevTools can identify layout shifts.

Modern Web Guidance recommends solutions such as:

reserving space for images
using skeleton loaders
avoiding unexpected DOM insertions
defining image dimensions
preventing late-loading UI elements

Instead of guessing, developers receive recommendations aligned with current web performance best practices.

🧪 Best Practices

Always profile before optimizing
Use Chrome DevTools to collect real performance data
Follow Modern Web Guidance instead of outdated optimization advice
Focus on Core Web Vitals that impact real users
Verify AI suggestions before applying them
Measure improvements after every optimization
Treat AI as a debugging assistant—not a replacement for understanding performance fundamentals

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Modern Web Guidance and Chrome DevTools for AI Agents represent an exciting step forward in web performance optimization.

In this article, you learned:

What Modern Web Guidance is
How Chrome DevTools for AI Agents works
How they complement each other
How they help identify and fix common performance issues

Take care!
And happy coding as always 🖥️

10 Vue Performance Mistakes I Still See in Production Apps

Jakub Andrzejewski — Mon, 15 Jun 2026 07:08:48 +0000

Performance has become one of the most important aspects of modern frontend development. Users expect websites to be fast and Google rewards fast websites.

And yet... even experienced Vue developers still introduce performance issues that can significantly impact user experience.

The tricky part? Most applications work perfectly fine during development.

Problems usually appear later:

larger datasets
slower devices
poor network conditions
increased application complexity

In this article, we'll look at 10 common Vue performance mistakes I still see in production applications and how to fix them.

Let's dive in.

🤔 Why Vue Performance Matters

Vue is already a highly optimized framework.

However, even the best framework cannot compensate for inefficient application code.

Poor performance can lead to:

slow page loads
delayed interactions
poor Core Web Vitals scores
increased battery usage
frustrated users

The good news?

Most performance issues can be fixed with relatively small changes.

🟢 Mistake #1: Using Deep Watchers Everywhere

A common mistake is enabling deep watchers on large objects.

Example:

watch(
  userData,
  () => {
    saveDraft()
  },
  {
    deep: true
  }
)

Deep watchers force Vue to traverse the entire object tree.

For large datasets this can become very expensive.

Instead:

watch specific properties
split large objects
use computed values when possible

🟢 Mistake #2: Making Everything Reactive

Not every piece of data needs reactivity.

I often see code like this:

const hugeDataset = ref(largeArray)

When the data rarely changes, Vue still needs to create reactive proxies.

For large collections this introduces unnecessary overhead.

A better approach:

const hugeDataset = shallowRef(largeArray)

Or even:

const hugeDataset = markRaw(largeArray)

when reactivity isn't needed at all.

🟢 Mistake #3: Creating New Objects Inside Computed Properties

Consider this:

const userInfo = computed(() => ({
  name: user.value.name,
  role: user.value.role
}))

A brand-new object is created every time the computed runs.

This can trigger unnecessary component updates.

Instead, prefer returning primitives when possible or memoizing expensive transformations.

🟢 Mistake #4: Using v-if Instead of v-show for Frequently Toggled Elements

Many developers use:

<div v-if="isOpen">
  Content
</div>

But if the element is shown and hidden frequently, Vue must repeatedly:

mount
render
destroy

A better option:

<div v-show="isOpen">
  Content
</div>

This simply toggles CSS visibility.

For frequently toggled UI elements, it's usually much faster.

🟢 Mistake #5: Rendering Huge Lists Without Virtualization

Rendering thousands of DOM nodes is expensive.

Example:

<div
  v-for="user in users"
  :key="user.id"
>
  {{ user.name }}
</div>

This might work with 100 items.

It won't feel great with 10,000.

Instead consider:

virtual scrolling
pagination
infinite loading

Libraries like Vue Virtual Scroller can dramatically improve performance.

🟢 Mistake #6: Lazy Loading Nothing

Many applications ship their entire codebase on the first page load.

Example:

import UserSettings from './UserSettings.vue'

This increases:

bundle size
download time
parse time

Instead:

const UserSettings = defineAsyncComponent(
  () => import('./UserSettings.vue')
)

Users only download code when it's actually needed.

🟢 Mistake #7: Fetching Data Sequentially

A surprisingly common issue:

const users = await fetchUsers()
const posts = await fetchPosts()
const comments = await fetchComments()

Each request waits for the previous one.

A faster approach:

const [users, posts, comments] =
  await Promise.all([
    fetchUsers(),
    fetchPosts(),
    fetchComments()
  ])

This can reduce loading times significantly.

🟢 Mistake #8: Forgetting About Image Optimization

Images are often the largest assets on a page.

Yet many applications still serve:

oversized images
uncompressed formats
images outside the viewport

For Vue and Nuxt applications:

use WebP or AVIF
lazy load images
generate responsive sizes

Image optimization frequently provides the biggest performance wins.

🟢 Mistake #9: Ignoring Component Re-Renders

A component may render far more often than expected.

For example:

<ExpensiveChart
  :data="chartData"
/>

If chartData changes reference on every update, the chart keeps re-rendering.

Common solutions:

stabilize references
use shallowRef
avoid unnecessary reactive updates
profile components with Vue DevTools

Small changes here can have a huge impact.

🟢 Mistake #10: Never Measuring Performance

The biggest mistake?

Not measuring anything.

Many teams optimize blindly.

Instead, regularly check:

Lighthouse
Core Web Vitals
Vue DevTools
Chrome Performance Panel
Network waterfalls

Performance work should be data-driven.

You can't improve what you don't measure.

🟢 Performance Checklist

Before shipping a Vue application, ask yourself:

✅ Am I using deep watchers only when necessary?

✅ Do all objects really need reactivity?

✅ Are large lists virtualized?

✅ Are routes and components lazy loaded?

✅ Are API requests running in parallel?

✅ Are images optimized?

✅ Have I measured actual performance?

If any answer is "no", there may be easy performance wins available.

🧪 Best Practices

Use shallowRef for large datasets
Avoid deep watchers whenever possible
Lazy load routes and heavy components
Virtualize large lists
Optimize images aggressively
Profile real-world user flows
Monitor Core Web Vitals
Measure before and after every optimization

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Vue is fast by default.

But performance problems often come from how we use the framework rather than the framework itself.

In this article, you learned:

10 common Vue performance mistakes
Why they impact real-world applications
How to identify them
Practical ways to fix them
Best practices for building faster Vue apps

Many of these issues are easy to overlook during development but become expensive at scale.

By avoiding these mistakes and measuring performance regularly, you can build applications that feel fast, responsive, and enjoyable to use.

Take care!
And happy coding as always 🖥️

Frontend Observability in Vue Apps with OpenTelemetry

Jakub Andrzejewski — Mon, 08 Jun 2026 08:59:35 +0000

As frontend applications become more complex, debugging production issues becomes increasingly difficult.

A user reports: "The page feels slow." or: "The dashboard sometimes freezes."

But when you check your logs... everything looks fine.

The problem is that traditional frontend monitoring often tells you what failed, but not why it happened.

This is where observability comes in. And one of the most popular tools for modern observability is OpenTelemetry.

In this article, we'll explore:

What frontend observability is
How it differs from traditional monitoring
Why OpenTelemetry is becoming the industry standard
How to add OpenTelemetry to a Vue application
Best practices for collecting useful telemetry

Let's dive in.

🤔 What Is Frontend Observability?

Observability is the ability to understand what's happening inside your application by collecting telemetry data.

Typically, this includes:

traces
metrics
logs

Unlike traditional monitoring, observability helps answer questions like:

Why is this page slow?
Which API request caused the delay?
What happened before the error occurred?
Which users are affected?

Instead of simply knowing that something failed...

👉 You can understand the entire chain of events that led to the problem.

🟢 Why Is Frontend Observability Important?

Most teams invest heavily in backend observability.

They track:

database queries
API latency
server errors
infrastructure metrics

But users interact with the frontend.

And many issues happen before the request even reaches the backend.

For example:

slow component rendering
blocked main thread
failed network requests
routing issues
third-party script delays

Without frontend observability these problems are often invisible.

🟢 What Is OpenTelemetry?

OpenTelemetry (often called OTel) is an open-source observability framework used to collect and export telemetry data.

It provides a standard way to collect:

traces
metrics
logs

And send them to tools such as:

Grafana
Jaeger
Datadog
New Relic
Honeycomb
Elastic

The biggest advantage? Vendor-neutral instrumentation.

You can change observability providers without rewriting your instrumentation.

🟢 How OpenTelemetry Helps Vue Applications

Imagine a user loads a dashboard.

Several things happen:

Route change
↓
Component mounts
↓
API request starts
↓
Data is fetched
↓
UI renders

Normally these events are disconnected.

With OpenTelemetry you can trace the entire flow.

This helps answer questions like:

Which API call slowed down the page?
How long did rendering take?
Which routes are causing performance issues?

🟢 Setting Up OpenTelemetry in Vue

Let's look at a simplified setup.

Install the required packages:

npm install \
  @opentelemetry/api \
  @opentelemetry/sdk-trace-web \
  @opentelemetry/instrumentation-fetch \
  @opentelemetry/instrumentation-xml-http-request

Basic initialization

import { WebTracerProvider } from '@opentelemetry/sdk-trace-web'

const provider = new WebTracerProvider()

provider.register()

This creates a tracer that can collect telemetry from the browser.

🟢 Creating Custom Traces

One of the most powerful features is custom tracing.

Example:

import { trace } from '@opentelemetry/api'

const tracer = trace.getTracer('vue-app')

Inside a component:

const span = tracer.startSpan('load-users')

try {
  await fetchUsers()
} finally {
  span.end()
}

Now you'll see exactly how long that operation took.

This becomes extremely useful when debugging production issues.

🟢 Tracking Route Performance

Vue Router is another excellent place to add tracing.

Example:

router.beforeEach((to, from, next) => {
  performance.mark('navigation-start')
  next()
})

router.afterEach(() => {
  performance.measure(
    'navigation',
    'navigation-start'
  )
})

Combined with OpenTelemetry exporters, this can help identify slow routes and navigation bottlenecks.

🟢 Monitoring API Requests

Many performance problems originate from network calls.

OpenTelemetry provides automatic instrumentation for:

Fetch API
XMLHttpRequest

Example:

registerInstrumentations({
  instrumentations: [
    new FetchInstrumentation()
  ]
})

Now requests can automatically generate traces.

You can see:

request duration
failures
dependencies between actions

without manually instrumenting every API call.

🧪 Best Practices

Instrument critical user flows first
Trace important API requests
Avoid collecting unnecessary telemetry
Sample traces in high-traffic applications
Correlate frontend traces with backend traces
Monitor route transitions and rendering bottlenecks
Focus on actionable insights rather than collecting everything

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Frontend observability helps you understand not just what went wrong, but why it happened.

As applications grow in complexity, logs and error tracking alone are often no longer enough.

OpenTelemetry gives you deeper visibility into your Vue application, helping you identify bottlenecks, improve performance, and deliver a better user experience.

Take care!
And happy coding as always 🖥️

State-Driven Animations in Vue: Create Smooth UI Transitions with Reactive State

Jakub Andrzejewski — Mon, 01 Jun 2026 09:54:37 +0000

Animations can make an application feel faster, smoother, and more polished. However, many developers think animations are only useful for things like:

page transitions
modals
enter/leave effects

But Vue provides another powerful pattern - State-driven animations. Instead of animating when elements are added or removed from the DOM, you animate changes in reactive state. This allows you to create rich interactive experiences while keeping your code declarative and easy to maintain.

In this article, we'll explore:

What state-driven animations are
How they differ from regular Vue transitions
What problems they solve
How to implement them in Vue
Best practices for creating smooth UI interactions

Let's dive in.

🤔 What Are State-Driven Animations?

Most Vue developers are familiar with the <Transition> component.

Example:

<Transition>
  <Modal v-if="isOpen" />
</Transition>

This animates an element when it enters or leaves the DOM.

But what if the element already exists and only its state changes? For example:

a progress bar grows
a card expands
a chart updates
a panel changes size
a value changes position

This is where state-driven animations shine.

Instead of animating DOM insertion or removal, you animate changes caused by reactive state.

🟢 What Problem Do State-Driven Animations Solve?

Without animations, state changes can feel abrupt.

Example:

<div :style="{ width: progress + '%' }"></div>

When progress changes:

progress.value = 80

The width instantly jumps.

This works technically... but it doesn't feel great.

🟢 A Simple Example

Let's create an animated progress bar.

<script setup lang="ts">
const progress = ref(20)

function increase() {
  progress.value += 20
}
</script>

<template>
  <button @click="increase">
    Increase Progress
  </button>

  <div class="progress-container">
    <div
      class="progress-bar"
      :style="{ width: `${progress}%` }"
    />
  </div>
</template>

CSS:

.progress-container {
  width: 100%;
  height: 12px;
  background: #eee;
}

.progress-bar {
  height: 100%;
  background: #42b883;
  transition: width 0.3s ease;
}

Now whenever progress changes, the bar animates smoothly.

The animation is entirely driven by reactive state.

🟢 Animating Multiple Properties

State-driven animations are not limited to width.

Example:

<div
  class="card"
  :style="{
    transform: expanded
      ? 'scale(1.1)'
      : 'scale(1)',
    opacity: expanded
      ? 1
      : 0.7
  }"
/>

CSS:

.card {
  transition:
    transform 0.3s ease,
    opacity 0.3s ease;
}

Now changing:

expanded.value = true

animates scale and opacity at the same time.

🟢 Using Vue Reactivity with Animations

One of the biggest advantages is that animations stay connected to Vue's reactivity system.

Example:

<script setup lang="ts">
const isActive = ref(false)
</script>

<template>
  <button @click="isActive = !isActive">
    Toggle
  </button>

  <div
    class="box"
    :class="{ active: isActive }"
  />
</template>

CSS:

.box {
  width: 100px;
  height: 100px;
  transition: all 0.4s ease;
}

.box.active {
  transform: rotate(180deg);
}

Vue handles state.

CSS handles animation.

The result is clean and maintainable.

🧪 Best Practices

Keep animations subtle and purposeful
Prefer CSS transitions for simple effects
Avoid animating expensive properties when possible
Use transforms instead of layout-changing properties when appropriate
Don't animate everything
Keep durations short (typically 200–400ms)
Use animations to communicate state changes, not distract users

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

State-driven animations are a powerful way to create smooth and engaging user experiences in Vue.

While <Transition> is perfect for entering and leaving elements, state-driven animations excel when existing elements need to react smoothly to changing data.

Used thoughtfully, they can make your applications feel significantly more responsive and professional.

Take care!
And happy coding as always 🖥️

Avoid Cross Module Dependencies with Dependency Cruiser

Jakub Andrzejewski — Mon, 25 May 2026 06:27:43 +0000

As applications grow, maintaining a clean architecture becomes increasingly difficult.

At first, everything feels manageable but after a few months (or years), projects often become full of:

circular dependencies
deeply coupled modules
messy import paths
forbidden cross-layer imports
architectural chaos

The worst part is that these problems usually grow silently over time.

This is where dependency-cruiser becomes incredibly useful. It helps you visualize and enforce rules for your project dependencies before things become unmaintainable.

In this article, we’ll explore:

What dependency-cruiser is
What problems it solves
How to set it up
Practical examples
How to enforce architectural boundaries

Let’s dive in.

🤔 What Is dependency-cruiser?

dependency-cruiser is a powerful tool for analyzing and validating dependencies in JavaScript and TypeScript projects.

It scans your project imports and helps you:

detect circular dependencies
enforce architecture rules
visualize dependency graphs
identify unused modules
prevent bad import patterns

Think of it like:

👉 “ESLint for your project architecture.”

🟢 What Problem Does dependency-cruiser Solve?

In large applications, dependencies can quickly become messy.

Example problems:

❌ Circular dependencies

A → B → C → A

These can cause:

runtime issues
undefined values
difficult debugging
unpredictable behavior

❌ Layer violations

Example:

components → api → components

Or:

ui → backend → ui

This breaks separation of concerns.

❌ Shared modules becoming dumping grounds

You often end up with:

/utils
/shared
/helpers

containing everything.

Over time:

dependencies become tangled
architecture loses structure

✅ dependency-cruiser helps enforce boundaries

You can define rules like:

“UI cannot import backend”
“Feature modules cannot depend on each other”
“No circular dependencies allowed”

And automatically validate them in CI.

🟢 Installing dependency-cruiser

Setup is very simple.

Install it:

npm install --save-dev dependency-cruiser

🟢 Generating Your First Dependency Graph

One of the coolest features is visualization.

Example:

npx depcruise src --include-only "^src" --output-type dot | dot -T svg > dependency-graph.svg

This generates a visual graph of your project dependencies.

You can quickly spot:

circular dependencies
overly connected modules
problematic architecture

In large projects, this is incredibly eye-opening.

🟢 Creating Rules

The real power comes from architecture validation.

Example config:

module.exports = {
  forbidden: [
    {
      name: 'no-circular',
      severity: 'error',
      from: {},
      to: {
        circular: true
      }
    }
  ]
}

Now dependency-cruiser will fail whenever circular dependencies appear.

🟢 Real-World Example: Enforcing Layered Architecture

Imagine this structure:

src/
├── components/
├── features/
├── api/
├── utils/

You may want:

👉 components should never import from api

Rule example:

module.exports = {
  forbidden: [
    {
      name: 'no-components-to-api',
      from: {
        path: '^src/components'
      },
      to: {
        path: '^src/api'
      }
    }
  ]
}

Now architecture rules become automated.

This is extremely valuable for:

large teams
enterprise projects
monorepos
long-term maintainability

🟢 Using dependency-cruiser with Vue Projects

dependency-cruiser works great with:

Vue
Nuxt
React
Angular
Node.js
TypeScript monorepos

For Vue apps, it’s especially useful when managing:

composables
feature modules
shared UI components
store architecture
layered frontend structure

Example issue it can prevent:

components → composables → components

Which can become very difficult to maintain later.

🟢 CI Integration

One of the best things about dependency-cruiser:

👉 It can run automatically in CI/CD pipelines.

Example:

npx depcruise src --validate .dependency-cruiser.js

Now pull requests fail when architecture rules are violated.

This prevents technical debt from growing silently.

🟢 Common Mistakes

❌ Creating overly strict rules too early

Start simple.

Too many restrictions can frustrate teams.

❌ Ignoring the reports

The tool is only useful if rules are actually enforced.

❌ Not visualizing dependencies

Graphs often reveal architecture problems immediately.

❌ Allowing shared folders to grow uncontrollably

dependency-cruiser helps expose this early.

🧪 Best Practices

Start with circular dependency detection
Gradually add architectural rules
Integrate validation into CI
Use dependency graphs regularly
Keep rules aligned with real architecture decisions
Avoid massive shared utility folders
Use the tool proactively — not only after problems appear

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

dependency-cruiser is an incredibly valuable tool for keeping project architecture healthy as applications grow.

Good architecture rarely happens accidentally.

Tools like dependency-cruiser help teams maintain structure, reduce technical debt, and prevent dependency chaos before it becomes a serious problem.

Take care!
And happy coding as always 🖥️

Avoid Unnecessary Re-renders in Vue with `v-memo`

Jakub Andrzejewski — Mon, 18 May 2026 09:21:34 +0000

When building Vue applications, performance usually feels great by default - Vue’s reactivity system is incredibly efficient.

But as applications grow larger, you may eventually run into situations where:

components re-render too often
large lists become expensive
UI updates feel sluggish
unnecessary computations happen repeatedly

This is where memoization becomes useful. And in Vue, one of the easiest ways to optimize rendering is with v-memo.

In this article, we’ll explore:

What memoization is
What problem it solves
How v-memo works in Vue
Real-world examples
Best practices and common mistakes

Let’s dive in.

🤔 What Is Memoization?

Memoization is an optimization technique where results are cached and reused instead of recalculating them again.

Instead of:

recomputing
re-rendering
recalculating

You simply use the cached version.

🟢 What Problem Does Memoization Solve?

In reactive applications, updates can trigger many re-renders even when most data has not changed for example:

Parent component updates
Entire list re-renders
Hundreds of child components update unnecessarily

This can hurt performance, responsiveness, and even battery usage on mobile devices.

Without memoization every update causes new rendering work - even for unchanged content.

With memoization Vue can skip rendering when dependencies stay the same which reduces DOM operations, Virtual DOM diffing, and in general component work.

🟢 What Is `v-memo` in Vue?

v-memo is a Vue directive that memoizes part of a template.

Basic example:

<div v-memo="[value]">
  {{ expensiveContent }}
</div>

Vue will only re-render this block when value changes. Otherwise Vue reuses the previous rendered result.

Let’s imagine a large user list.

Without v-memo

<script setup lang="ts">
const users = ref([
  { id: 1, name: 'John' },
  { id: 2, name: 'Alice' }
])

const counter = ref(0)
</script>

<template>
  <button @click="counter++">
    {{ counter }}
  </button>

  <div
    v-for="user in users"
    :key="user.id"
  >
    {{ user.name }}
  </div>
</template>

Every counter update re-renders the whole list even though users never changed.

With v-memo we can:

<script setup lang="ts">
const users = ref([
  { id: 1, name: 'John' },
  { id: 2, name: 'Alice' }
])

const counter = ref(0)
</script>

<template>
  <button @click="counter++">
    {{ counter }}
  </button>

  <div
    v-for="user in users"
    :key="user.id"
    v-memo="[user.id]"
  >
    {{ user.name }}
  </div>
</template>

And now counter updates still happen but unchanged list items are skipped. This becomes extremely valuable for large lists, dashboards, or tables.

🟢 When NOT to Use It

v-memo is not needed everywhere as Vue is already highly optimized.

Avoid using it for tiny components, static content, or premature optimization as overusing memoization can:

reduce readability
make debugging harder
introduce stale UI bugs

🧪 Best Practices

Use v-memo only for measurable bottlenecks
Great for large dynamic lists
Keep dependency arrays minimal
Avoid premature optimization
Profile performance before optimizing
Combine with virtual scrolling for huge datasets
Prefer stable keys and predictable state updates

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Memoization is a powerful optimization technique that helps avoid unnecessary work.

In this article, you learned:

What memoization is
What problem it solves
How Vue’s v-memo works
Practical examples for lists and components
When to use it — and when not to

Take care!
And happy coding as always 🖥️

Why Loaders Matter for Performance

Jakub Andrzejewski — Mon, 11 May 2026 09:29:43 +0000

When developers think about performance optimization, they usually focus on things like:

lazy loading
caching
image optimization
bundle size

And while those things absolutely matter there’s another area that heavily impacts user experience -> Loading states and layout stability.

A badly implemented loading experience can make an app feel slow, jumpy, or frustrating to use. This is strongly connected to an important Core Web Vital metric Cumulative Layout Shift (CLS).

In this article, we’ll explore:

What CLS is
Why loaders are critical for perceived performance
How poor loading states hurt UX
Practical examples in Vue
Best practices for stable layouts

Let’s dive in.

🤔 What Is Cumulative Layout Shift (CLS)?

CLS measures how much elements unexpectedly move during page loading.

Example of bad CLS:

Text suddenly jumps down
Buttons move while you try to click
Images appear late and push content around

We’ve all experienced websites like this:

👉 You try to click something… and suddenly the layout shifts. Extremely annoying.

Why does this happen? Usually because:

content loads asynchronously
elements have no reserved space
loaders are missing
images don’t define dimensions
components suddenly appear

Why does CLS matter? Because it affects user experience, accessibility, or mobile usability (and obviously Google Core Web Vitals). Even if your app is technically fast poor layout stability can make it feel slow.

👉 Users care more about perceived performance than actual milliseconds.

A good loader communicates progress, prevents layout jumping, and makes apps feel responsive

A bad or missing loader creates uncertainty. Users start thinking:

“Did the app freeze?”
“Is something broken?”
“Why is everything moving?”

🟢 Implementing proper loaders in Vue

Let's take a look at the following example:

<script setup lang="ts">
const users = ref([])
const loading = ref(true)

onMounted(async () => {
  users.value = await fetchUsers()
  loading.value = false
})
</script>

<template>
  <div v-if="loading" class="skeleton-list">
    <div
      v-for="n in 5"
      :key="n"
      class="skeleton-card"
    />
  </div>

  <UserCard
    v-else
    v-for="user in users"
    :key="user.id"
    :user="user"
  />
</template>

<style scoped>
.skeleton-card {
  height: 120px;
  border-radius: 12px;
  margin-bottom: 16px;
}
</style>

We fetch users, but when the fetch is in progress we display the same hard coded number of loaders/skeletons. When the users are loaded there is no layout shift as it occupies the same space improving perceived performance and User Experience.

If we don't know how many results there will be, we have to assume some number but it is still better than not having skeletons at all :)

Many apps still use simple spinners or text/icon loaders like:

<div>Loading...</div>

But modern UX usually prefers Skeleton loaders because they mimic final layout, reduce layout shift, and improve perceived speed.

🧪 Best Practices

Prefer skeleton loaders over tiny spinners
Reserve space before content loads
Keep loading and final layouts similar
Always define image dimensions
Avoid injecting large content suddenly
Test CLS using Lighthouse or Core Web Vitals tools
Think about perceived performance — not just raw speed

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Loaders are much more important than most developers realize.

In this article, you learned:

What Cumulative Layout Shift (CLS) is
Why poor loading states hurt UX
How skeleton loaders improve perceived performance
How to avoid layout jumping in Vue and other frameworks
Best practices for stable, responsive interfaces

Fast apps are great.

But apps that feel smooth and stable are what users truly remember.

Take care!
And happy coding as always 🖥️

How to Safely Allow Inline Scripts Without Breaking Security with CSP Nonce

Jakub Andrzejewski — Mon, 27 Apr 2026 06:46:57 +0000

When building modern web applications, security is not optional. One of the most important protections you can add is a Content Security Policy (CSP).

But here’s the catch:

👉 CSP often blocks inline scripts and styles — which can break your app.

So how do you keep your app secure without disabling useful features?

That’s where CSP nonce comes in - it allows you to safely execute inline code without opening security holes.

In this article, we’ll explore:

What CSP nonce is
What problem it solves
How to implement it
How it works automatically in Nuxt with nuxt-security
Best practices and common pitfalls

Let’s dive in.

🤔 What Is CSP Nonce?

A nonce (short for number used once) is a unique, random value generated for each request.

It is used in CSP to explicitly allow trusted inline scripts or styles.

Example:

<script nonce="abc123">
  console.log('Secure inline script')
</script>

And in your HTTP headers:

Content-Security-Policy: script-src 'nonce-abc123'

The browser will only execute scripts that have a matching nonce.

CSP nonce is a whitelist mechanism:

Only scripts with the correct nonce are allowed
Everything else is blocked
The nonce changes on every request

This makes it extremely effective against XSS (Cross-Site Scripting) attacks.

CSP nonce is commonly used for:

SSR frameworks - Injecting initial state, Hydration scripts
Analytics / tracking snippets - Inline scripts required by providers
Critical inline scripts - Small scripts needed before app bootstraps

🟢 What Problem Does CSP Nonce Solve?

Without nonce, you usually face a trade-off:

❌ Allow inline scripts (unsafe)

Content-Security-Policy: script-src 'unsafe-inline'

Problem:

Opens the door to XSS attacks
Any injected script can run

❌ Block inline scripts completely

Content-Security-Policy: script-src 'self'

Problem:

breaks inline event handlers
breaks injected scripts (SSR hydration, state)
breaks some frameworks

🟢 How to Implement CSP Nonce

The process is relatively simple but let's break it down and explain each step individually.

Step 1: Generate a nonce per request

Example (Node.js):

import crypto from 'crypto'

function generateNonce() {
  return crypto.randomBytes(16).toString('base64')
}

Step 2: Add it to response headers

const nonce = generateNonce()

res.setHeader(
  'Content-Security-Policy',
  `script-src 'nonce-${nonce}'`
)

Step 3: Inject it into your HTML

<script nonce="{{nonce}}">
  window.__INITIAL_STATE__ = {}
</script>

⚠️ Critical rule

The nonce in the header and HTML must match exactly. Otherwise, script will be blocked and app may break silently.

🟢 CSP Nonce in Nuxt (with nuxt-security)

If you’re using Nuxt, things get much easier thanks to nuxt-security module that can:

Automatically generate nonce per request
Inject it into CSP headers
Attach it to scripts/styles

It makes it much easier to work with CSP nonces in Nuxt. Let's take a look at the following configuration:

export default defineNuxtConfig({
  modules: ['nuxt-security'],
  security: {
    headers: {
      contentSecurityPolicy: {
        'script-src': [
          "'self'",
          "'nonce-{{nonce}}'"
        ]
      }
    }
  }
})

What happens automatically:

Nuxt generates a nonce per request
Replaces {{nonce}} in headers
Applies nonce to inline scripts

You don’t need to manually wire everything

You can read more here:
https://nuxt-security.vercel.app/

🟢 Common Mistakes

Let's take a look at the list of common mistakes to understand what to look for:

❌ Reusing the same nonce - Nonce must be unique per request and cryptographically random
❌ Forgetting to apply nonce in HTML - if you only set CSP header the scripts will still be blocked
❌ Mixing nonce with unsafe-inline - script-src 'unsafe-inline' 'nonce-abc'
❌ Caching issues - if HTML is cached nonce may not match header

🧪 Best Practices

Generate nonce per request
Use secure randomness (crypto)
Never reuse nonce
Avoid unsafe-inline
Use frameworks/tools (like nuxt-security)
Test CSP in report-only mode first
Monitor browser console for CSP violations

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

CSP nonce is a powerful mechanism that allows you to safely use inline scripts while maintaining strong security.

In this article, you learned:

What CSP nonce is and how it works
What problem it solves (security vs flexibility)
How to implement it step by step
How Nuxt + nuxt-security handle it automatically
Common mistakes and best practices

Take care!
And happy coding as always 🖥️

Flexible Code Without Losing Type Safety with TS Generics

Jakub Andrzejewski — Mon, 30 Mar 2026 09:03:13 +0000

When working with TypeScript, you quickly run into a common problem:

👉 You want your code to be reusable, but also type-safe.

At first, it’s tempting to use any to make things flexible… but that comes at a cost:

You lose type safety
You lose autocomplete
You introduce hidden bugs

This is exactly the problem that TypeScript Generics solve.

They let you write reusable code without sacrificing type safety.

In this article, we’ll explore:

What Generics are
What problem they solve
Practical examples you’ll actually use
Best practices to avoid common mistakes

Let’s dive in.

🤔 Problem with type reusability

When you want your function to be reusable, you usually end up with this any approach:

function identity(value: any): any {
  return value
}

It works but it also comes with problems such as no type safety, no IntelliSense, and can easily lead to break things.

The second problem is code duplication:

function identityString(value: string): string {
  return value
}

function identityNumber(value: number): number {
  return value
}

With this approach, we are breaking the Don't Repeat Yourself (DRY) rule which also makes the code harder to maintain and less scalable.

🤔 Solution: TypeScript Generics

Generics allow you to create components, functions, or classes that work with multiple types, while still preserving full type information.

Think of them as:

👉 “Type placeholders” that get filled in later

Basic example:

function identity<T>(value: T): T {
  return value
}

Here:

T is a generic type
It represents whatever type you pass in

Usage:

identity<string>("hello") // string
identity<number>(123)    // number

TypeScript automatically knows what comes out based on what goes in.

🟢 Practical Examples

Let’s look at real-world scenarios where generics shine.

✅ Example 1: Reusable API Response Type

Very common pattern in frontend apps:

type ApiResponse<T> = {
  data: T
  error: string | null
}

Usage:

type User = {
  id: number
  name: string
}

const response: ApiResponse<User> = {
  data: { id: 1, name: "John" },
  error: null
}

Now your API types are consistent, reusable, and fully typed.

✅ Example 2: Generic Array Helper

function getFirstItem<T>(arr: T[]): T {
  return arr[0]
}

Usage:

const number = getFirstItem([1, 2, 3]) // number
const string = getFirstItem(["a", "b"]) // string

TypeScript knows exactly what type is returned.

✅ Example 3: Generic Props in Vue

Check out my other article where I have explained this topic in more details here.

✅ Example 4: Constraining Generics

Sometimes you want flexibility — but with rules.

function getLength<T extends { length: number }>(value: T) {
  return value.length
}

Usage:

getLength("hello") // ✅
getLength([1, 2, 3]) // ✅
getLength(123) // ❌ error

With this approach, you ensure flexibility but also controlled structure.

✅ Example 5: Keyof + Generics

function getProperty<T, K extends keyof T>(obj: T, key: K) {
  return obj[key]
}

Usage:

const user = {
  id: 1,
  name: "John"
}

getProperty(user, "name") // ✅
getProperty(user, "age") // ❌ error

This is extremely powerful for forms, dynamic access, or utilities.

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

TypeScript Generics are one of the most powerful features in the language. They let you write code that is both flexible and safe — which is exactly what you want in modern applications.

Once you start using them properly, it’s hard to go back.

Take care!
And happy coding as always 🖥️

When You Should Use Vue Teleport

Jakub Andrzejewski — Mon, 23 Mar 2026 09:36:56 +0000

When building modern Vue applications, not everything fits neatly inside your component tree. Some UI elements — like modals, tooltips, dropdowns, or overlays — often need to escape their parent container due to:

z-index issues
overflow constraints
stacking context problems
layout limitations

This is where Vue Teleport becomes incredibly useful as it allows you to render part of your component outside of its DOM hierarchy, while still keeping it logically connected to the component.

In this article, we’ll explore:

What Vue Teleport is
When you should use it
Real-world use cases (like dialogs and overlays)
What defer Teleport does and when to use it

Let’s dive in.

🤔 What Is Vue Teleport?

Vue Teleport is a built-in component that allows you to render content in a different part of the DOM than where it is declared.

Basic example:

<Teleport to="body">
  <div class="modal">
    I am rendered in body!
  </div>
</Teleport>

Even though this code exists inside a component, the rendered HTML is moved to <body>. Teleport changes where elements are rendered, not how they behave. This means that reactivity still works, events still work, and component logic stays intact.

Teleport is purely about DOM placement.

🟢 When Should You Use Vue Teleport?

Teleport is ideal when UI elements need to visually break out of their parent container.

✅ Modals / Dialogs

Modals are the most common use case.

Without Teleport, modals can break due to:

overflow: hidden
nested containers
stacking issues

Example:

<Teleport to="body">
  <div class="modal-backdrop">
    <div class="modal">
      Modal content
    </div>
  </div>
</Teleport>

✅ Tooltips & Dropdowns

Dropdowns and tooltips often need to appear above everything else.

Teleport helps avoid:

clipping inside parent containers
z-index conflicts

✅ Notifications / Toasts

Global UI elements like notifications should not depend on local layout.

<Teleport to="#notifications">
  <Toast message="Saved!" />
</Teleport>

✅ Third-party UI Libraries (Real Example)

Libraries like Reka UI use Teleport internally for components such as dialogs.

Example usage pattern:

<DialogRoot>
  <DialogTrigger>Open</DialogTrigger>

  <DialogPortal>
    <DialogOverlay />
    <DialogContent>
      Dialog content
    </DialogContent>
  </DialogPortal>
</DialogRoot>

Under the hood, DialogPortal uses Teleport to render content outside the component tree — usually into <body>.

This ensures:

Proper layering
Accessibility compliance
Correct focus management

This pattern is standard for headless UI libraries.

🟢 Deferred Teleport (`defer`)

Vue also provides an advanced feature: deferred teleport.

Example:

<Teleport to="#target" defer>
  <div>Deferred content</div>
</Teleport>

Normally, Teleport tries to move content immediately but sometimes the target element does not exist yet or it is rendered later (e.g., in SSR or layouts)

With defer, Vue waits until the target exists before teleporting.

🟢 Common Mistakes When Using Teleport

There are few things we should take care when using Teleport:

Overusing Teleport - avoid using Teleport for regular layout, simple components, or static UI.
Forgetting Accessibility - teleport does not solve focus trapping, keyboard navigation, or ARIA roles.
Styling issues - Teleported content is no longer inside the same DOM tree which means scoped styles may not apply and parent CSS may not affect the component.

🧪 Best Practices

Use Teleport primarily for overlays and global UI
Combine with proper focus management
Use defer when working with dynamic targets
Prefer UI libraries (like Reka UI) for complex patterns
Keep Teleport usage minimal and intentional

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Vue Teleport is a powerful tool for handling UI elements that need to exist outside normal DOM hierarchy.

Teleport helps you solve layout problems cleanly while keeping your component logic simple and maintainable.

Use it wisely — and your UI architecture will become much more flexible.

Take care!
And happy coding as always 🖥️

Reusable Architecture for Large Applications with Nuxt Layers

Jakub Andrzejewski — Mon, 16 Mar 2026 09:51:13 +0000

As applications grow, managing shared code across projects becomes increasingly difficult. Teams often face problems like:

Duplicated logic across repositories
Inconsistent project structure
Hard-to-maintain design systems
Repeated configuration setup

This is where Nuxt Layers become extremely useful.

In this article, we’ll explore:

What Nuxt Layers are
How they work
How to use them to reuse code across projects
How they help build scalable architecture
Potential tradeoffs and when to avoid them

Let’s dive in.

🤔 What Are Nuxt Layers?

Nuxt Layers allow one Nuxt project to extend another using the extends feature.

In practice, this means you can create a base layer containing shared logic, and multiple applications can build on top of it.

A layer can include:

Components
Composables
Pages
Layouts
Middleware
Configuration
Modules

Think of layers as reusable Nuxt building blocks.

Example architecture:

base-layer/
  components/
  composables/
  layouts/
  nuxt.config.ts

app/
  pages/
  nuxt.config.ts

The application extends the base layer.

🟢 Creating a Nuxt Layer

A layer is essentially a Nuxt project that other projects can extend.

Example layer structure:

ui-layer/
  components/
    AppButton.vue
  composables/
    useTheme.ts
  nuxt.config.ts

Then in your application:

export default defineNuxtConfig({
  extends: ['../ui-layer']
})

Now everything inside the layer becomes available inside your app.

For example, the AppButton component can be used directly:

<AppButton>
  Click me
</AppButton>

No additional imports required. This makes sharing UI systems across multiple apps much easier.

🟢 Reusing Code Across Multiple Projects

One of the biggest benefits of Nuxt Layers is code reuse across multiple repositories.

For example, you may create layers for:

UI components
Authentication logic
Analytics integrations
Design systems
API composables

Example layered architecture:

core-layer
  composables/
  utils/

ui-layer
  components/
  layouts/

marketing-app
admin-app
dashboard-app

Each application extends the shared layers.

Example configuration:

export default defineNuxtConfig({
  extends: [
    '../core-layer',
    '../ui-layer'
  ]
})

This ensures that:

Shared code lives in one place
Updates propagate across projects
Teams maintain consistent patterns

It’s particularly useful for large organizations managing multiple applications.

🟢 Using Layers for Scalable Architecture

Nuxt Layers also help structure large applications.

Instead of a single large codebase, you can divide your system into logical layers.

Example architecture:

design-system-layer
business-logic-layer
feature-layer
app-layer

Each layer builds on top of the previous one.

Example:

design-system-layer
  components/
  styles/

business-layer
  composables/

feature-layer
  pages/
  components/

app-layer
  pages/

Then your main application config:

export default defineNuxtConfig({
  extends: [
    '../design-system-layer',
    '../business-layer',
    '../feature-layer'
  ]
})

This approach:

Improves maintainability
Encourages separation of concerns
Helps teams scale development

It becomes easier to reason about the architecture of large Nuxt projects.

🟢 Layer Overrides and Merging

One powerful aspect of Nuxt Layers is that later layers override earlier ones.

For example:

base-layer/components/Header.vue
app/components/Header.vue

The application version overrides the base layer component.

This allows you to:

Provide defaults in layers
Customize behavior in applications

Configuration is also merged automatically.

Example:

export default defineNuxtConfig({
  runtimeConfig: {
    apiBase: '/api'
  }
})

If multiple layers define runtimeConfig, Nuxt merges them.

This merging behavior makes layers flexible and customizable.

⚠️ Tradeoffs of Nuxt Layers

While layers are powerful, they introduce some complexity.

Increased Architectural Complexity

When many layers are involved, it can become harder to understand:

Where components come from
Which layer overrides which
How configuration is merged

This can slow onboarding for new developers.

Debugging Can Be Harder

If a component behaves unexpectedly, you may need to check multiple layers.

Example problem:

Component defined in:
- layer A
- layer B
- application

Understanding which one is active requires careful inspection.

Tooling and IDE Navigation

Depending on your editor setup, navigating across layers may be less straightforward than working within a single project.

Although modern Nuxt tooling is improving, it still requires good project organization.

Overengineering Risk

For small projects, layers may be unnecessary.

If you only have one application, layers may introduce more complexity than value.

They shine most when:

Managing multiple applications
Building reusable systems
Maintaining design systems

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Nuxt Layers introduce a powerful way to structure and reuse code across applications. When used correctly, layers can transform a collection of applications into a well-organized ecosystem of reusable building blocks.

But like any architectural tool, they should be applied thoughtfully and only when they truly provide value.

Take care!
And happy coding as always 🖥️

How Vue Protects Your App Against Injections

Jakub Andrzejewski — Mon, 09 Mar 2026 07:52:51 +0000

Security is one of the most important aspects of modern web development. Applications that process user input must protect themselves against various forms of attacks — especially injection attacks.

Luckily, Vue provides several built-in mechanisms that help protect your application from common vulnerabilities like:

Cross-Site Scripting (XSS)
HTML injection
Attribute injection

These protections are built into the framework, meaning that in many cases Vue secures your app by default.

In this article, we’ll explore:

How Vue escapes interpolated content
Why v-html can be dangerous
How Vue protects against attribute injection
Best practices for keeping your Vue apps secure

Let’s dive in.

🤔 What Are Injection Attacks?

Injection attacks occur when an attacker manages to insert malicious code into an application that is later executed in the browser.

A common example is Cross-Site Scripting (XSS).

Example of malicious input:

<script>alert('Hacked')</script>

If your application renders this directly into the DOM, the script executes in the user’s browser.

That could allow attackers to:

Steal authentication tokens
Hijack user sessions
Inject malicious UI
Redirect users to phishing pages

This is why modern frameworks must protect developers against unsafe rendering.

Vue does exactly that.

🟢 Vue Automatic HTML Escaping

By default, Vue escapes all interpolated content.

Example:

<p>{{ userInput }}</p>

If userInput contains:

<script>alert('Hacked')</script>

Vue will render it as text:

<p>&lt;script&gt;alert('Hacked')&lt;/script&gt;</p>

Instead of executing the script.

This simple rule protects against most XSS attacks is that Interpolation ({{ }}) is always safe.

The browser sees escaped text rather than executable HTML.

🟢 Template Compilation Safety

Vue templates are compiled into JavaScript functions.

However, Vue only compiles trusted templates — the ones written by developers.

For example:

<div>{{ message }}</div>

This template becomes optimized render functions internally.

But Vue does not compile user-provided templates dynamically. Doing so would be extremely dangerous.

Bad example (never do this):

app.component('UnsafeComponent', {
  template: userInput
})

If userInput contains malicious JavaScript, it could execute inside your app.

The rule of thumb here is to never use user input as a Vue template.

🟢 Attribute Injection Protection

Vue also escapes values used inside HTML attributes.

Example:

<div :title="userInput"></div>

If userInput contains:

" onmouseover="alert('Hacked')

Vue safely escapes it before inserting it into the DOM.

Instead of executing malicious JavaScript, the browser treats it as a simple string value.

This protects against:

Event handler injection
Attribute-based XSS attacks

🟢 URL Injection Protection

Another attack vector involves injecting dangerous URLs like:

javascript:alert('Hacked')

Example:

<a :href="userLink">Click me</a>

Vue does not automatically sanitize URLs, because valid URLs may include many protocols.

This means developers must validate URLs themselves.

Safe practice:

<script setup>
function sanitizeUrl(url) {
  if (url.startsWith('http://') || url.startsWith('https://')) {
    return url
  }
  return '#'
}
</script>

<template>
  <a :href="sanitizeUrl(userLink)">Open link</a>
</template>

This prevents dangerous protocols like:

javascript:
data:
vbscript:

🔴 The Danger of `v-html`

While Vue escapes interpolation by default, v-html bypasses that protection.

Example:

<div v-html="userContent"></div>

If userContent contains:

<script>alert('XSS')</script>

The script will execute.

That makes v-html the most common source of XSS vulnerabilities in Vue apps.

Only use it when:

Rendering trusted HTML
Rendering sanitized content

Example with sanitization library:

import DOMPurify from 'dompurify'

const safeHtml = DOMPurify.sanitize(userContent)

Then:

<div v-html="safeHtml"></div>

🧪 Best Security Practices for Vue Apps

Even though Vue protects your application by default, developers should still follow security best practices.

1.Prefer interpolation

Safe:

{{ content }}

Avoid:

v-html="content"

2.Sanitize external HTML

If you must render HTML, use sanitization tools like:

DOMPurify
sanitize-html

3.Validate URLs

Never blindly render user-provided links.

Always validate allowed protocols.

4.Avoid dynamic template compilation

Never use user input inside Vue templates.

5.Use CSP (Content Security Policy)

A strong CSP header can mitigate many injection attacks.

Example policy:

Content-Security-Policy: script-src 'self'

This prevents execution of inline malicious scripts.

📖 Learn more

If you would like to learn more about Vue, Nuxt, JavaScript or other useful technologies, checkout VueSchool by clicking this link or by clicking the image below:

It covers most important concepts while building modern Vue or Nuxt applications that can help you in your daily work or side projects 😉

🧪 Advance skills

A certification boosts your skills, builds credibility, and opens doors to new opportunities. Whether you're advancing your career or switching paths, it's a smart step toward success.

Check out Certificates.dev by clicking this link or by clicking the image below:

Invest in yourself—get certified in Vue.js, JavaScript, Nuxt, Angular, React, and more!

✅ Summary

Vue includes several built-in protections against injection attacks.

These mechanisms make Vue a secure-by-default framework, but security still depends on responsible developer practices.

When used correctly, Vue helps ensure your application stays safe from common injection vulnerabilities.

Take care!
And happy coding as always 🖥️

DEV Community: Jakub Andrzejewski

Fix Web Performance Issues Faster with Modern Web Guidance and Chrome DevTools for AI Agents

🤔 What Is Modern Web Guidance?

🟢 What Is Chrome DevTools for AI Agents?

🟢 How It Works Together

🟢 Example: Finding a Long JavaScript Task

🟢 Example: Fixing Layout Shifts

🧪 Best Practices

📖 Learn more

🧪 Advance skills

✅ Summary

10 Vue Performance Mistakes I Still See in Production Apps

🤔 Why Vue Performance Matters

🟢 Mistake #1: Using Deep Watchers Everywhere

🟢 Mistake #2: Making Everything Reactive

🟢 Mistake #3: Creating New Objects Inside Computed Properties

🟢 Mistake #4: Using v-if Instead of v-show for Frequently Toggled Elements

🟢 Mistake #5: Rendering Huge Lists Without Virtualization

🟢 Mistake #6: Lazy Loading Nothing

🟢 Mistake #7: Fetching Data Sequentially

🟢 Mistake #8: Forgetting About Image Optimization

🟢 Mistake #9: Ignoring Component Re-Renders

🟢 Mistake #10: Never Measuring Performance

🟢 Performance Checklist

🧪 Best Practices

📖 Learn more

🧪 Advance skills

✅ Summary

Frontend Observability in Vue Apps with OpenTelemetry

🤔 What Is Frontend Observability?

🟢 Why Is Frontend Observability Important?

🟢 What Is OpenTelemetry?

🟢 How OpenTelemetry Helps Vue Applications

🟢 Setting Up OpenTelemetry in Vue

Basic initialization

🟢 Creating Custom Traces

🟢 Tracking Route Performance

🟢 Monitoring API Requests

🧪 Best Practices

📖 Learn more

🧪 Advance skills

✅ Summary

State-Driven Animations in Vue: Create Smooth UI Transitions with Reactive State

🤔 What Are State-Driven Animations?

🟢 What Problem Do State-Driven Animations Solve?

🟢 A Simple Example

🟢 Animating Multiple Properties

🟢 Using Vue Reactivity with Animations

🧪 Best Practices

📖 Learn more

🧪 Advance skills

✅ Summary

Avoid Cross Module Dependencies with Dependency Cruiser

🤔 What Is dependency-cruiser?

🟢 What Problem Does dependency-cruiser Solve?

❌ Circular dependencies

❌ Layer violations

❌ Shared modules becoming dumping grounds

✅ dependency-cruiser helps enforce boundaries

🟢 Installing dependency-cruiser

🟢 Generating Your First Dependency Graph

🟢 Creating Rules

🟢 Real-World Example: Enforcing Layered Architecture

🟢 Using dependency-cruiser with Vue Projects

🟢 CI Integration

🟢 Common Mistakes

❌ Creating overly strict rules too early

❌ Ignoring the reports

❌ Not visualizing dependencies

❌ Allowing shared folders to grow uncontrollably

🧪 Best Practices

📖 Learn more

🧪 Advance skills

✅ Summary

Avoid Unnecessary Re-renders in Vue with `v-memo`

🤔 What Is Memoization?

🟢 What Problem Does Memoization Solve?

🟢 What Is v-memo in Vue?

🟢 When NOT to Use It

🧪 Best Practices

🟢 What Is `v-memo` in Vue?

🟢 Deferred Teleport (`defer`)