如何在JavaScript中與Web Worker通信
创建Web Worker并使用postMessage发送消息;2. 主线程通过onmessage或addEventListener接收消息;3. Worker内部监听message事件处理数据并回传;4. 使用terminate()或self.close()终止Worker;5. 通过onerror监听错误;通信基于异步消息传递,数据被复制而非共享,适用于CPU密集型任务,且不能访问DOM,必须通过消息机制实现主线程与Worker间交互。
Communicating with a Web Worker in JavaScript is done through message passing using the postMessage()
method and listening for messages with the onmessage
event handler. Web Workers run in the background, separate from the main UI thread, so they can’t access the DOM or variables directly. Instead, you send and receive data asynchronously via messages.

Here’s how to set up and use communication between your main script and a Web Worker:
1. Creating and Sending Messages to a Web Worker
First, create a new Web Worker by passing the path to a JavaScript file:

const worker = new Worker('worker.js');
Then, send data to the worker using postMessage()
:
worker.postMessage('Hello Worker');
You can send more complex data like objects or arrays:

worker.postMessage({ command: 'start', data: [1, 2, 3, 4, 5] });
Note: Only structured-clonable data (like strings, numbers, objects, arrays) can be passed. Functions and DOM elements cannot be sent.
2. Receiving Messages from the Web Worker
In the main thread, listen for responses using the onmessage
event:
worker.onmessage = function(event) { console.log('Message from worker:', event.data); };
Or use addEventListener
(preferred for multiple listeners):
worker.addEventListener('message', function(event) { console.log('Received:', event.data); });
3. Handling Messages Inside the Web Worker
Inside worker.js
, listen for messages from the main thread:
self.onmessage = function(event) { console.log('Message received:', event.data); // Process data const result = event.data.data.map(x => x * 2); // Send result back self.postMessage({ result: result }); };
Again, you can also use addEventListener
:
self.addEventListener('message', function(event) { // Do work... self.postMessage('Work completed'); });
4. Terminating a Web Worker
When you’re done, clean up by terminating the worker from the main thread:
worker.terminate();
This immediately stops the worker, even if it’s in the middle of an operation.
Alternatively, the worker can terminate itself:
self.close();
5. Error Handling
You can also listen for errors in the worker:
worker.onerror = function(error) { console.error('Worker error:', error.message); };
Errors in the worker won’t crash the main page but should still be handled.
Example: Full Workflow
main.js
const worker = new Worker('worker.js'); worker.postMessage({ numbers: [1, 2, 3, 4, 5] }); worker.onmessage = function(event) { console.log('Result:', event.data); // Output: { doubled: [2, 4, 6, 8, 10] } }; worker.onerror = function(error) { console.error('Error:', error.message); };
worker.js
self.onmessage = function(event) { const data = event.data.numbers; const doubled = data.map(n => n * 2); self.postMessage({ doubled: doubled }); };
Key Points to Remember
- Communication is asynchronous and based on events.
- Data is copied, not shared (though
Transferable
objects likeArrayBuffer
can be transferred for better performance). - Web Workers cannot access
window
,document
, or the DOM. - Use workers for CPU-intensive tasks like parsing large data, image processing, or complex calculations.
Basically, it’s all about postMessage
and onmessage
. Set up listeners on both sides, pass data as needed, and keep the main thread responsive.
以上是如何在JavaScript中與Web Worker通信的詳細內容。更多資訊請關注PHP中文網其他相關文章!

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