依赖包安装：npm install cheerio download async superagent superagent-charset mkdirp
superagent ajax请求库
cheerio node版的jquery，获取dom节点
download 下载文件库
superagent-charset 设置字符集，不然获取到的htmlDoc会有中文乱码
async mapLimit控制请求并发数，第一个回调是linkArr每个item项都执行的函数，处理完想要的数据后并return，第二个回调是linkArr每项都执行完后执行，返回一个err，和results，results就是包裹着第一个函数return值的数组（有点像promise.all）

const request = require('superagent')
require('superagent-charset')(request)
const cheerio = require('cheerio')
const download = require('download')
const mkdirp = require('mkdirp')
const async = require('async')

var linkArr = [],
    domain = 'https://www.tupianzj.com',
    saveImgPath = './img/';

let config = {};
    config.num = 3;

request('GET', `https://www.tupianzj.com/meinv/xiezhen/list_179_${config.num}.html`) 
  .end(function(err, res){
    if (!err) {

        let $ = cheerio.load(res.text);

        let links = $('.list_con_box_ul li>a');

        for (let i = 0; i < links.length; i++) {
            linkArr.push(domain + $(links[i]).attr('href'))
        }
        
        async.mapLimit(linkArr,1,async function(url) {

            let { text } = await request(url).charset('gbk'),
                $ = cheerio.load(text),
                $pages = $('.pages li>a'),
                page_num = $pages.first().text().replace(/\D/g,''),
                item_link = $pages.eq(-2).attr('href'),
                itemLinkArr = [],
                itemDomain = url.replace(/\d+\.html/,''),
                dirname = saveImgPath + $('.list_con>h1').text();
            //创建目录
            mkdirp(dirname);
            for (let i = 1; i <= page_num; i++) {

                let sign = i === 1 ? '' : '_'+i;
                let link = itemDomain + item_link.replace(/_\d+/,sign);
                itemLinkArr.push(link);
            }

            return {itemLinkArr,dirname};
            
        },(err, results) => {

            if (err) throw err

            let allLinkArr = [],allCount,
                index = 0,
                count = 0,
                indexManager = {};
            for (let i = 0; i < results.length; i++) {
                index += results[i].itemLinkArr.length;
                allLinkArr = allLinkArr.concat(results[i].itemLinkArr);
                indexManager[index] = results[i].dirname;
                
            }
            allCount = allLinkArr.length;
            async.mapLimit(allLinkArr,1,async function(url){
    
                let dirIndex = getDirIndex(++count,indexManager);
                let { text } = await request(url);
                let $ = cheerio.load(text);
                let img_src = $('#bigpic img').attr('src');
                await download( img_src, indexManager[dirIndex]); 
                console.log(`图片下载:${count}/${allCount}`)
            },(err,results) => {
                if (err) throw err
            })
                

        })
        
    }else{
        console.log(err)
    }
});

function getDirIndex(count,obj){
    for (let key in obj) {

        if(count <= key){
            return key;
        }
    }
}