http://www.cnblogs.com/dolphinX/p/7715268.html---好文 /** * Copyright 2017 Google Inc. All rights reserved. * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * *     http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */'use strict';const puppeteer = require('puppeteer');(async() => {  const browser = await puppeteer.launch();  const page = await browser.newPage();  // Define a window.onCustomEvent function on the page.  await page.exposeFunction('onCustomEvent', e => {    console.log(`${e.type} fired`, e.detail || '');  });  /**   * Attach an event listener to page to capture a custom event on page load/navigation.   * @param {string} type Event name.   * @return {!Promise}   */  function listenFor(type) {    return page.evaluateOnNewDocument(type => {//定义页面加载和导航时要执行的函数      document.addEventListener(type, e => {        window.onCustomEvent({type, detail: e.detail});      });    }, type);  }  await listenFor('app-ready'); // Listen for "app-ready" custom event on page load.  await page.goto('https://www.chromestatus.com/features', {waitUntil: 'networkidle0'});  await browser.close();})();