Worker.onmessage

Worker 接口的onmessage属性表示一个event handler事件处理函数，当message 事件发生时，该函数被调用。这些事件所属MessageEvent类型，且当Worker子线程返回一条消息时被调用（比如：从DedicatedWorkerGlobalScope.postMessage (en-US)函数发出的信息）

注意: 消息被装载到 message事件对象的data属性。（译者：即传递的消息参数将被赋值给onmessage处理函数的事件参数e中的data属性）

语法

myWorker.onmessage = function(e) { ... }

范例

下面的代码片段示范用Worker() 构造函数创建一个Worker对象。当表单的first输入框的值变更时，消息被传递给worker。myWorker.onmessage函数用来处理从worker回传的消息。

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

first.onchange = function() {
  myWorker.postMessage([first.value,second.value]);
  console.log('Message posted to worker');
}

myWorker.onmessage = function(e) {
  result.textContent = e.data;
  console.log('Message received from worker');
}

在worker.js中, onmessage 函数用来接收从主线程传递过来的信息:

onmessage = function(e) {
  console.log('Message received from main script');
  var workerResult = 'Result: ' + (e.data[0] * e.data[1]);
  console.log('Posting message back to main script');
  postMessage(workerResult);
}

请注意，主线程中必须以myWorker.onmessage方式调用, 反之 worker.js 脚本中, 只需定义 onmessage, 因为worker.js全域有效(DedicatedWorkerGlobalScope).

完整范例，请参考Basic dedicated worker example (run dedicated worker).

规范

规范	状态	注释
HTML Living Standard Worker.onmessage	Living Standard	No change from Unknown.
Unknown Worker.onmessage	Unknown	Initial definition.

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参阅

Worker 接口所属。