DEV Community

Cover image for Web Worker, Service Worker, and Worklets: A Comprehensive Guide
Bharat Singh Rajput
Bharat Singh Rajput

Posted on

Web Worker, Service Worker, and Worklets: A Comprehensive Guide

Web development is an ever-evolving field with constant innovations in web technologies to make web applications faster, more efficient, and user-friendly. One such innovation is the introduction of Web Workers, Service Workers, and Worklets.

In this blog post, we will discuss these three concepts in detail and see how they work together to improve the performance of web applications.

Web Worker

A Web Worker is a JavaScript script that runs in the background, independent of the main thread. Web Workers were introduced in HTML5 to help web developers overcome the limitations of single-threaded JavaScript execution.

Web Workers enable concurrent processing of tasks, making web applications faster and more responsive. They work by offloading computationally intensive tasks from the main thread, allowing it to focus on the user interface and other tasks that require immediate attention.

Web Workers are useful in scenarios where tasks take a long time to execute, such as data processing, encryption/decryption, and image processing. By using Web Workers, web developers can prevent the main thread from getting blocked, resulting in a smoother user experience.

Service Worker

Service Workers are another important concept in web development. Service Workers are JavaScript files that run in the background and enable offline functionality, push notifications, and caching of resources.

Service Workers act as a proxy between the web application and the network, intercepting network requests made by the application. They allow web applications to work offline by caching the resources required for the application to function.

Service Workers can also be used to push notifications to users even when the application is not running. This feature is particularly useful for web applications that need to send real-time notifications to users.


Worklets are a new concept introduced in the CSS Houdini specification. Worklets enable web developers to extend the CSS rendering engine, allowing for custom CSS properties, functions, and animations.

Worklets are lightweight JavaScript modules that run in a separate thread from the main thread. They provide a way for web developers to create custom, high-performance animations and effects without affecting the main thread's performance.

Worklets are an exciting addition to web development, as they enable web developers to create new and unique visual effects that were previously not possible with CSS alone.


Web Workers, Service Workers, and Worklets are powerful concepts that help improve the performance of web applications. Web Workers enable concurrent processing of tasks, Service Workers enable offline functionality and push notifications, and Worklets enable custom animations and effects.

By using these three concepts together, web developers can create fast, responsive, and user-friendly web applications that deliver an exceptional user experience.

We hope this post has provided a comprehensive overview of Web Workers, Service Workers, and Worklets. As always, we encourage you to continue learning and exploring these and other web development concepts to stay ahead of the curve.

Top comments (2)

technicalgalaxy profile image
High-Tech Galaxy

Nice 👍

bharat5604 profile image
Bharat Singh Rajput • Edited

I am writing another blog on this specific worker. i will post this soon stay tuned. for quick understanding you can watch this video and read this official documentation