Javascript网络工作者：为什么我需要postMessage两次来触发事件？ [英] Javascript web workers: why do I need to postMessage twice to trigger event?
问题描述
我是Javascript和网络编程的新手。我想找出网络工作者，并有以下代码（在chrome中运行）：
I am a newcomer to Javascript and web programming in general. I am trying to figure out web workers, and have the following code (running in chrome):
worker_example.html
worker_example.html
<!DOCTYPE html>
<html>
<head>
<script type="text/javascript" src="worker_example.js"></script>
</head>
<html>
worker_example.js
worker_example.js
var worker = new Worker("worker.js");
worker.addEventListener('message', function(e) {
document.write("hello");
}, false);
worker.postMessage("");
worker.js
worker.js
// self.postMessage("");
我的问题是为什么不 worker.postMessage（）触发事件？但是，如果我取消注释worker.js中的单行，一切正常。
My question is why doesn't worker.postMessage("") trigger the event? If I uncomment the single line in worker.js, however, everything works fine.
推荐答案
附加到<$ c的事件监听器$ c> worker 侦听从工作人员到父页面的消息。您还需要在worker 中注册一个监听器。
The event listener attached to worker listens for messages coming from the worker to the parent page. You need to register a listener in the worker as well.
parent.js
parent.js
var worker = new Worker('worker.js');
worker.addEventListener('message', function (e) {
console.log(e.data);
});
worker.postMessage('marco');
worker.js
worker.js
self.addEventListener('message', function (e) {
self.postMessage(e.data + ' polo');
});
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