[JavaScript知识库]react中使用web worker

Web Worker 的作用，就是为 JavaScript 创造多线程环境，允许主线程创建 Worker 线程，将一些任务分配给后者运行。

一、Web Worker 具体用法

import React, { Component } from 'react';

import worker_script from './worker-script';

export default class PageHome extends Component {
  constructor(props) {
    super(props);
    this.state = {};
  }

  componentDidMount() {
    const worker = new Worker(worker_script);
    console.log(worker);
    worker.onmessage = function (event) {
      console.log(`Received message ${event.data}`);
    };
    // worker.postMessage('dadada')
  }
}

worder-script.js

const workercode = () => {
  self.onmessage = function (e) {
    console.log('Message received from main script');
    let workerResult = `Received from main: ${e.data}`;
    console.log('Posting message back to main script');
    self.postMessage(workerResult);
  };

  self.postMessage('workerResult');
};

let code = workercode.toString();
code = code.substring(code.indexOf('{') + 1, code.lastIndexOf('}'));

const blob = new Blob([code], { type: 'application/javascript' });
const worker_script = URL.createObjectURL(blob);

export default worker_script;

二、注意事项

1、非同源限制，主线程代码与Worker线程代码必须同源才能一起正常工作

2、Worker线程任务需要等待主线程任务结束才能进行

3、可以主动关闭Worker线程。如果是多页应用的话，离开了Worker页面，Worker 也会停止工作

4、脚本限制，worker线程不能执行alert、confirm，但可以使用?XMLHttpRequest?对象发出ajax请求