js中的webworker

webworker的作用类似于java的多线程

以独立文件的形式运行webworker

index.html

<!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>Document</title>
</head>
<body>
    <div id="showBox"></div>
    <script>
        if(window.Worker) {
            var worker = new Worker("./test.js");
            worker.postMessage(10);

            worker.onmessage = function(event) {
                document.getElementById("showBox").innerText = event.data;
                if(event.data == 10) {
                    worker.terminate(); // 终止worker
                }
            }
        }else{
            alert("你的浏览器不支持worker");
        }
    </script>
</body>
</html>

test.js

var i = 0, count = 0; 

self.onmessage = function(e) {
    count = e.data;
}

function countNumber() {
    if(i < count){
        i = i + 1;
        self.postMessage(i); // 将信息发送到主线程上
    }
    console.log(i);
    setTimeout(countNumber, 500)
}
countNumber();