//延时函数
function sleep(delay) {
return new Promise((resolve, reject) => {
setTimeout(() => {
try {
resolve(1)
} catch (e) {
reject(0)
}
}, delay)
})
}
const puppeteer = require(‘puppeteer‘);
puppeteer.launch({
ignoreHTTPSErrors:true,
headless:false,slowMo:250,
timeout:0}).then(async browser => {
let page = await browser.newPage();
await page.setJavaScriptEnabled(true);
await page.goto("https://www.jd.com/");
const searchInput = await page.$("#key");
await searchInput.focus(); //定位到搜索框
await page.keyboard.type("手机");
const searchBtn = await page.$(".button");
await searchBtn.click();
await page.waitForSelector(‘.gl-item‘); //等待元素加载之后，否则获取不异步加载的元素
const links = await page.$$eval(‘.gl-item > .gl-i-wrap > .p-img > a‘, links => {
return links.map(a => {
return {
href: a.href.trim(),
title: a.title
}
});
});
page.close();
const aTags = links.splice(0, 10);
for (var i = 1; i < aTags.length; i++) {
page = await browser.newPage()
page.setJavaScriptEnabled(true);
await page.setViewport({width:1920, height:1080});
var a = aTags[i];
await page.goto(a.href, {timeout:0}); //防止页面太长，加载超时
//注入代码，慢慢把滚动条滑到最底部，保证所有的元素被全部加载
let scrollEnable = true;
let scrollStep = 500; //每次滚动的步长
while (scrollEnable) {
scrollEnable = await page.evaluate((scrollStep) => {
let scrollTop = document.scrollingElement.scrollTop;
document.scrollingElement.scrollTop = scrollTop + scrollStep;
return document.body.clientHeight > scrollTop + 1080 ? true : false
}, scrollStep);
await sleep(100);
}
await page.waitForSelector("#footer-2014", {timeout:0}); //判断是否到达底部了
let filename = "images/items-"+i+".png";
//这里有个Puppeteer的bug一直没有解决，发现截图的高度最大只能是16384px， 超出部分被截掉了。
await page.screenshot({path:filename, fullPage:true});
page.close();
}
browser.close();
});
