1-6、谈谈你对 Web Worker 的理解

Web Worker 就是运行在后台的 js，可以通过 postMessage 返回结果。所有的 Worker 必须与创建者同源。

Worker - Web API 接口参考 | MDN (mozilla.org)
mdn/simple-web-worker: A simple web worker test. (github.com)
Web Workers basic example (mdn.github.io)

// main.js
const first = document.querySelector('#number1');
const second = document.querySelector('#number2');
const result = document.querySelector('.result');
if (window.Worker) {
  const myWorker = new Worker("worker.js");
  first.onchange = function() {
    myWorker.postMessage([first.value, second.value]);
    console.log('Message posted to worker');
  }
  second.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');
  }
} else {
  console.log('Your browser doesn\'t support web workers.');
}

// work.js
onmessage = function(e) {
  console.log('Worker: Message received from main script');
  const result = e.data[0] * e.data[1];
  if (isNaN(result)) {
    postMessage('Please write two numbers');
  } else {
    const workerResult = 'Result: ' + result;
    console.log('Worker: Posting message back to main script');
    postMessage(workerResult);
  }
}