Node.js中理解asyncmap函数 ，爬取王者荣耀荣耀官网壁纸400多张

async/mapLimit函数理解

const phantom = require('phantom')
const express = require('express');
const app = express();
const axios = require('axios');
const isPlainObject = require('lodash/isPlainObject');
const qs = require('qs')
const Cookies = require('js-cookie')
const fs = require('fs');
const cheerio = require('cheerio');
const request = require('request');

//express服务器，
let server = app.listen(2000, function () {
    let host = server.address().address;
    let port = server.address().port;
    console.log('Your App is running at http://%s:%s', host, port);
});

//封装axios
const http = axios.create({
    timeout: 1000 * 180,
    withCredentials: true
})

/**
 * 请求拦截
 */
http.interceptors.request.use(config => {
    config.headers['Accept-Language'] = Cookies.get('language') || 'zh-CN'
    // console.log('token',Cookies.get('token'))
    // config.headers['Authorization'] = Cookies.get('token') || ''  //加token
    // if(config.headers['Authorization'] == '') {
    //     clearLoginInfo()
    //     router.replace({ name: 'login' })
    // }
    // 默认参数
    var defaults = {}
    // 防止缓存，GET请求默认带_t参数
    if (config.method === 'get') {
        config.params = {
            ...config.params,
            ...{'_t': new Date().getTime()}
        }
    }
    if (isPlainObject(config.params)) {
        config.params = {
            ...defaults,
            ...config.params
        }
    }
    if (isPlainObject(config.data)) {
        config.data = {
            ...defaults,
            ...config.data
        }
        if (/^application\/x-www-form-urlencoded/.test(config.headers['content-type'])) {
            config.data = qs.stringify(config.data)
        }
    }
    return config
}, error => {
    return Promise.reject(error)
})

/**
 * 响应拦截
 */
http.interceptors.response.use(response => {
    return response;
}, error => {
    console.error(error)
    return Promise.reject(error)
})

class stealData {

    constructor() {
        this.base_url = 'https://pvp.qq.com/web201605/wallpaper.shtml#%23%23'//爬取网址
        this.listAll = []
    }

    async init() {
        try {
            await this.geData()//打开网页
            // await this.getUrl()//打开网页
        } catch (e) {
            console.log(e);
        }
    }

    async geData() {
        await this.getUrl(0)
    }

    async getUrl(i) {
        console.log(i)
        let list = []
        let params = {
            page: i
        }
        http.get('https://apps.game.qq.com/cgi-bin/ams/module/ishow/V1.0/query/workList_inc.cgi?activityId=2735&sVerifyCode=ABCD&sDataType=JSON&iListNum=20&totalpage=0&iOrder=0&iSortNumClose=1&jsoncallback=jQuery17107547180061056307_1599185179163&iAMSActivityId=51991&_everyRead=true&iTypeId=2&iFlowId=267733&iActId=2735&iModuleId=2735&_=', {params: params}).then(res => {
            let a = JSON.parse(res.data.match(/({(\S*)})/)[1])
            this.down(a.List,i)

        })

    }
    sleep(time) {
        return new Promise((resolve) => {
            console.log(`自动睡眠中，${time / 1000}秒后重新发送请求......`)
            setTimeout(() => {
                resolve();
            }, time);
        });
    }//请求延迟时间，防止ip被封
    async down(src,index) {

        for (let i = 0;i<src.length;i++){
            let url = decodeURIComponent(src[i].sProdImgNo_7).replace("/200","/0")
            console.log('url',url)
            let ext = url.split('.').pop().substr(0,3)
            try {
                console.log(`开始写入第${i+index*20+1}张`)
                await request(url).pipe(fs.createWriteStream(`./Wangzhe/${new Date().getTime()}.${ext}`));
                await this.sleep(3000)//防止被封
                console.log(`写入成功`)

            }catch (e) {
                console.log('下载出错：',e)
            }
        }
        if(index<22){
            await this.getUrl(++index)
        }

    }

}

const thief = new stealData('xxx_url');
thief.init();