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HTML Web Workers

Using Web Workers

HTML web workers run scripts in background threads, improving performance.

Introduction to Web Workers

Web Workers allow you to run JavaScript in parallel threads, effectively enabling you to perform heavy computations without blocking the user interface. This is essential for web applications requiring complex calculations or data processing, ensuring a smooth and responsive user experience.

Creating a Basic Web Worker

To create a web worker, you need to write your JavaScript code in a separate file. Let's create a simple worker that calculates the sum of numbers.

First, create a file named worker.js:

In this script, the worker listens for messages (using self.onmessage) and calculates the sum of an array of numbers, sending the result back to the main script using self.postMessage.

Using a Web Worker in Your HTML

Next, you will integrate the web worker into your HTML file. Below is an example of how to do this:

In this example, when the button is clicked, an array of numbers is sent to the web worker. The worker processes the data and sends back the result, which is displayed in the <div> with the ID result.

Benefits of Using Web Workers

  • Improved Performance: Offload heavy computations to a separate thread, preventing UI blocking.
  • Better User Experience: Keep the main thread responsive for user interactions.
  • Scalability: Handle large data processing efficiently.

Limitations of Web Workers

  • No DOM Access: Web workers cannot access the DOM directly. They can only communicate with the main thread using messages.
  • Limited API Access: Only certain APIs are available inside a worker, such as WebSockets, but not local storage or cookies.
  • Overhead: Starting a worker has some overhead, so it's best used for long-running tasks.

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