# 安装async
npm i async --save

# 安装完成
+ async@3.2.0

const mapLimit = require('async/mapLimit');
let musicId = [1, 2, 3];
mapLimit(musicId, 2, (item, callback) => {
    setTimeout(()=>{
        console.log(item);
        callback(null, item);
    },1000)
}, (err, results) => {
    console.log(results);
});

//index.js
const puppeteer = require('puppeteer');
const mapLimit = require('async/mapLimit');
//准备的音乐id数组
let musicId = [1407551413, 1303289043, 1417862046];
//并发次数为3
mapLimit(musicId, 3, (item, callback) => {
    (async () => {
        //并发执行爬取代码，返回结果
        let info = await selectInfo(item);
        callback(null, info);
    })();
}, (err, results) => {
    //三首音乐爬取完成再返回结果
    console.log(results);
});

//定义函数，内部返回Promise
async function selectInfo(id) {
    return new Promise(async (resolve, reject) => {
        const browser = await puppeteer.launch({
            timeout: 15000,
            ignoreHTTPSErrors: true,
            devtools: true,
            headless: true,
            args: [
                '-–disable-dev-shm-usage',
                '-–disable-setuid-sandbox',
                '-–no-first-run',
                '--no-sandbox',
                '-–no-zygote',
                '-–single-process'
            ]
        });
        const page = await browser.newPage();
        //同样的域名不同id
        await page.goto(`https://music.163.com/#/song?id=${id}`);
        const iframe = await page.frames().find(f => f.name() === 'contentFrame');
        const musicComment = await iframe.$('.cmmts.j-flag');
        let commentList = await iframe.evaluate((e) => {
            let comment = Array.from(e.getElementsByClassName('cnt f-brk'));
            //只获取前五条
            return comment.map((item) => item.innerText).filter((item, index) => index <= 5);
        }, musicComment);
        await browser.close();
        //返回当前音乐爬取的数据
        resolve(commentList);
    })
}

# 爬取评论内容
[
  [
    '李荣浩：网易云音乐的朋友们 欢迎收听我的新歌《麻雀》',
    '李小年1223P：我在电动车论坛等得好辛苦。',......
  ],
  [
    'Liam_BZ：唢呐倒是个神奇的东西\n中国人的红白喜事，从生到死\n一根铜管全能吹出来',......
  ],
  [
    '写蘑菇的小菇凉：他说——\n如果不想改变的话，请不要改变。',
    'angliaqin：起床？不光起床吧，还听他歌入睡的'......
  ]
]