检查多个createWriteStream的结尾

Question

我的节点应用程序出现问题。因此，我的react应用程序将服务器需要在本地下载的视频列表发送到服务器。每个fs.createWriteStream结束时如何响应我的React应用程序？预先感谢！

    const express = require('express');
const fs = require('fs');
const bodyParser = require('body-parser');
const ytdl = require('ytdl-core');
const app = express();
var cors = require('cors')


app.use(bodyParser.json());
app.use(cors());
app.get('/', (req, res, next) => {
    res.send('<form action="/add-product" method="POST"><input name="product" /><button type="submit">Add Code</button></form>')
})
app.post('/get-title', (req, res, next) => {
    ytdl.getInfo(req.body.url, (err, info) => {
        if(err)
        {
            res.send(err)
        }
        else
        res.send({ title: info.title,
        thumbnail:info.thumbnail_url
        })
    })
})
app.post('/createmp3', (req, res, next) => {

    req.body.videos.forEach(video => {
        console.log(`Se incarca ${video.title}`);
        ytdl(video.url, { format: 'audioonly' })
            .pipe(fs.createWriteStream(`music/${video.title}.wav`).on('close',()=>{
                console.log(`gata ${video.title}`);
            }))
    })

})
app.listen(1234, () => {
    console.log('The server has successfully started!!');
})