web worker的了解

如，MDN文档中介绍的那样，使用demo如下

<!DOCTYPE html>

<html lang="en">

<head>

<meta charset="UTF-8">

<meta name="viewport" content="width=device-width, initial-scale=1.0">

<meta http-equiv="X-UA-Compatible" content="ie=edge">

<title>webworker-demo</title>

</head>

<body>

<input id="first" type="text" />

<br />

<input type="text" id="second">

</body>

<script>

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

first.onchange = function () {

// myWorker.terminate();

myWorker.postMessage([first.value, 2]);

console.time();

console.log('Message posted to worker');

}

second.onchange = function () {

// myWorker.terminate();

console.time();

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');

console.log(e.data)

console.timeEnd();

}

</script>

</html>

worker.js，为了模拟计算过程的耗时，使用代码如下：

onmessage = function (e) {

console.log('Message received from main script');

var workerResult = (e.data[0] * e.data[1]);

var now = Date.now();

while (Date.now() - now < 5 * 1000) {

//延迟五秒

}

console.log('Posting message back to main script');

postMessage(workerResult);

}

总结：我们可以把计算过程负责耗时的操作放入worker的线程中。让这个worker线程去计算，这样就计算过程中就不会卡住js线程的异步任务队列正常运行。new Worker(url), 操作时浏览器会去加载这个URL地址指向的js。

待续...