nodejs trying to get remote file to open to user - node.js

Question

Wondering what I am doing wrong here. All i want is for the mp3 which I have wired in to be downloaded to the user.
My ideal solution would be able to add a mp3 to the front of this.
const express = require('express');
var fs = require('fs');
request = require('request');
const http = require("http");
const https = require("https");
router.get('/a/:url(*)', (req, res) =>{
res.set({
"Content-Type": "audio/mp3",
// 'Transfer-Encoding': 'chunk',
// 'Content-Disposition': 'attachment'
});
const file = fs.createWriteStream("audio.mp3");
var url = req.params.url.substr(0);
console.log(url);
https.get('https://storage.googleapis.com/ad-system/testfolder/OUTOFAREA.mp3', response => {
response.pipe(file);
});
https.get(url, response => {
response.pipe(file);
});
file.push(res);
});
module.exports = router;
error I am getting is
TypeError: file.push is not a function
at router.get (/root/adstichrplayer/server/routes/podcast.js:131:10)
at Layer.handle [as handle_request] (/root/node_modules/express/lib/router/layer.js:95:5)
at next (/root/node_modules/express/lib/router/route.js:137:13)
at Route.dispatch (/root/node_modules/express/lib/router/route.js:112:3)
at Layer.handle [as handle_request] (/root/node_modules/express/lib/router/layer.js:95:5)
at /root/node_modules/express/lib/router/index.js:281:22
at param (/root/node_modules/express/lib/router/index.js:354:14)
at param (/root/node_modules/express/lib/router/index.js:365:14)
at param (/root/node_modules/express/lib/router/index.js:365:14)
at Function.process_params (/root/node_modules/express/lib/router/index.js:410:3)
at next (/root/node_modules/express/lib/router/index.js:275:10)
at Function.handle (/root/node_modules/express/lib/router/index.js:174:3)
at router (/root/node_modules/express/lib/router/index.js:47:12)
at Layer.handle [as handle_request] (/root/node_modules/express/lib/router/layer.js:95:5)
at trim_prefix (/root/node_modules/express/lib/router/index.js:317:13)
at /root/node_modules/express/lib/router/index.js:284:7

Answer 1

You are trying to use .push on a Writeable stream. Only streams that implement a Readable interface can call .push.
If you don't specifically need to persist the file to disk, there's no reason to create the WriteStream. You can pipe directly to Express' res object:
router.get('/a/:url(*)', (req, res) => {
res.set({
'Content-Type': 'audio/mp3',
// 'Transfer-Encoding': 'chunk',
// 'Content-Disposition': 'attachment'
});
const url = req.params.url.substr(0);
console.log(url);
https.get(url, mp3Response => {
// pipe response from HTTP request to Express res object
mp3Response.pipe(res);
});
});