Web workers, separate threads from the main thread

Web Worker is a commonly used technology in HTML5. It is a JavaScript thread running in the browser, which can run JavaScript code in a context other than the main thread. This technique can help developers separate time-consuming tasks from the main thread, thereby improving page responsiveness.

The main advantage of Web Workers is that they can handle time-consuming tasks such as computationally intensive operations, network requests, and large amounts of data processing without blocking the page UI. By placing these tasks in a separate thread, you can ensure that the main thread remains highly responsive while doing work without blocking problems.

Using Web Worker does not require too complicated code, only a few simple lines can complete many tasks. Here are the basic steps to use a Web Worker:

1. Create a Worker object and pass the path of the JavaScript file as a parameter to the constructor.

var myWorker = new Worker('worker.js');

2. Define a callback function in the Worker.js file onmessageto process messages passed from the main thread, which can be any JavaScript objects.

self.onmessage = function(e) {
  var data = e.data;

  // Handle incoming message data...

  self.postMessage('Processed: ' + data);
};

3. In the main thread, postMessage()pass the data to the Worker through the method.

myWorker.postMessage('Data to process');

onmessage4. Process the passed data in the callback function of the Worker , and postMessage()pass the result back to the main thread through the method.

self.onmessage = function(e) {
  var data = e.data;

  // Perform calculations on data...

  self.postMessage('Processed: ' + data);
};

These are the basic steps for using Web Workers, but there are many other advanced uses that extend this technique even further. For example, we can create sub-Workers in Worker for more efficient multi-threaded programming, or share Workers between multiple browser windows by using SharedWorker.

In summary, Web Workers are a very useful technology that can improve the performance and responsiveness of JavaScript-based web applications. While the technology has many powerful features, it also requires care to avoid misuse. Because too many workers may cause the browser to run out of memory, thereby reducing application performance.