用request，cheerio进行网页图片下载

网页图片下载
request node.js中模块 支持http，https和重定向；
cheerio获取目标html里的img标签；
fs：node.js中内置模块 ，可以操作文件，用于对系统文件及目录进行读写操作。所有方法分为同步和异步两种方法。

const fs=require('fs')
const request = require('request');
const cheerio = require('cheerio');
function patu(url) {
request(url, function (error, response, body) {
console.log('error:', error); // Print the error if one occurred
console.log('statusCode:', response && response.statusCode); // Print the response status code if a response was received

const $ = cheerio.load(body);
let num = [];
$('img').each((i,e)=>{
num.push($(e).attr('src'))
})
for (let index = 0; index < num.length; index++) {
if(num[index].indexOf('http')!==-1){
let p=num[index].substr(num[index].length-4);
request(num[index]).pipe(fs.createWriteStream(`./img/${index}${p}`))
}
else{
num[index]="http:"+num[index];
// console.log(num[index])
let p=num[index].substr(num[index].length-4);
request(num[index]).pipe(fs.createWriteStream(`./img/${index}${p}`))
}
}
});
}
//调用函数；
patu('https://www.qunar.com')