业务场景

一个考试系统，需要在用户切换窗口或者最小化的时候依然保持倒计时正常进行

技术

webWorker多线程

工具代码

function create(f) {
  var blob = new Blob(['(' + f +')()']);
  var url = window.URL.createObjectURL(blob);
  var worker = new Worker(url);
  return worker;
}
  
export const createWorker = (callback, time) => {
  var pollingWorker = create(`function (e) {
    setInterval(function () {
      this.postMessage(null)
    }, ${time})
  }`);
  pollingWorker.onmessage = callback
  return pollingWorker;
}

export const stopWorker = (vm) => {
	try {
		vm&&vm.terminate()
	} catch (err) {
		console.log(err)
	}
}

用法

// 引入
import {createWorker, stopWorker} from '...'
// 创建
const worker = createWorker(() => {
	//做要做的事
}, 1000)
// 清除
/*
*	worker的值还在这个不同于定时器
*/
stopWorker(worker)