const puppeteer = require('puppeteer');
(async () => {
 const browser = await puppeteer.launch();//打開瀏覽器
 const page = await browser.newPage();//打開一個空白頁
 await page.goto('https://example.com');//在地址欄輸入網址并等待加載
 await page.screenshot({path: 'example.png'});//截個圖
 await browser.close();//關掉瀏覽器
})();

const puppeteer = require('puppeteer');
const account = `123456@qq.com`;
const password = `123456`;
(async () => {
 const browser = await puppeteer.launch();//打開瀏覽器
 const page = await browser.newPage();//打開一個空白頁
 await page.goto('https://www.douban.com/');//打開豆瓣網站
 await page.type('#form_email', account); 
 await page.type('#form_password', password);
 await page.click('.bn-submit');
 await page.waitForNavigation({
 waitUntil: 'load'
 });//等待頁面加載出來，等同于window.onload
 await page.screenshot({path: 'example.png'});//截個圖
 await browser.close();//關掉瀏覽器
})();

const browser = await puppeteer.launch({headless: false});//打開有界面的瀏覽器

...
 await page.waitForNavigation({
 waitUntil: 'load'
 });//等待頁面加載出來，等同于window.onload
//代碼中監聽跳轉事件
if(page.url() === 'https://www.douban.com/accounts/login'){ 
 //登錄不成功
 console.log('需要輸入驗證碼');
 //等待再一次跳轉
 while(true){
 await page.waitForNavigation({
 waitUntil: 'load'
 })
 console.log(page.url())
 if(page.url() === 'https://www.douban.com/'){
 console.log('登錄成功');
 break;
 }
 }
 }