Inline Web Workers: When and How to Use Them?

Inline Web Workers: A Comprehensive Guide

While web workers are typically defined in separate JavaScript files, there is a method to create them inline within the same HTML file. This approach is advantageous when aiming to minimize the number of separate files for distribution, especially when using tools like the closure compiler for code optimization.

Creating Inline Web Workers

Inline web workers utilize Blob() to create a URL handle to the worker code as a string. This allows the worker to be included directly in the HTML file. Here's a complete example:

HTML with Inline Worker Code:

<code class="html">
<script id="worker1" type="javascript/worker">
  // This script won't be parsed by JS engines due to its type.
  self.onmessage = function(e) {
    self.postMessage('msg from worker');
  };
</script></code>

Main JavaScript Code:

<code class="javascript">var blob = new Blob([
  document.querySelector('#worker1').textContent
], { type: "text/javascript" });

// Use window.webkitURL.createObjectURL() for Chrome versions below 11.
var worker = new Worker(window.URL.createObjectURL(blob));
worker.onmessage = function(e) {
  console.log("Received: " + e.data);
};
worker.postMessage("hello"); // Start the worker.</code>

In this example, the inline worker code is defined within the <script> tag with the type attribute set to "javascript/worker". The main JavaScript code then creates a Blob object from the worker code and uses window.URL.createObjectURL() to create a URL handle for the worker.</script>

Benefits and Use Cases

Inline web workers offer several benefits:

• Combining workers and main code into a single file for optimized distribution and reduced HTTP requests.
• Enhanced security as inline worker code cannot be accessed by external sites.

Some possible use cases for inline web workers include:

• Long-running computations that require offloading from the main thread.
• Handling time-sensitive tasks without interrupting the main thread.
• Isolating specific code for security or maintainability purposes.

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