NodeJS - Download MP3 file one at a time - node.js

Question

Im trying to make a quick node script to download MP3s from a RSS feed. At the moment I have this :
const https = require('https');
const xml2js = require('xml2js');
const parser = new xml2js.Parser();
const fs = require('fs');
const URL_TO_PARSE = 'https://some-rss.feed.xml';
const req = https.get(URL_TO_PARSE, async (res) => {
let xml = '';
res.on('data', (stream) => {
xml = xml + stream;
});
res.on('end', () => {
parser.parseString(xml, async (err, result) => {
if (err) {
console.log(err);
} else {
let items = result.rss.channel[0].item;
await Promise.all(items.map(async (item) => {
let title = item.title[0];
let enclosure = item.enclosure[0];
let url = enclosure.$.url;
let filepath = `./${title}`;
console.log(`Downloading ${title} to ${filepath}`);
await download_audio_file(url, filepath);
}));
}
});
});
});
const download_audio_file = async (url, filepath) => {
https.get(url, (res) => {
const writeStream = fs.createWriteStream(filepath);
res.pipe(writeStream);
writeStream.on('finish', () => {
writeStream.close();
console.log('File downloaded');
Promise.resolve();
});
writeStream.on('error', (err) => {
console.log(err);
Promise.reject(err);
});
})
But it currently tried to download each one at the same time. Is there a better way to write this to download just one at a time - and possibly also track the % progress?

Answer 1

I see 2 problems with your code.
The first one is that download_audio_file is not returning a promise that resolves when the file is fully downloaded.
You can fix that with this refactored version:
const download_audio_file = async (url, filepath) => {
const promise = new Promise((resolve, reject) => {
https.get(url, (res) => {
const writeStream = fs.createWriteStream(filepath);
res.pipe(writeStream);
writeStream.on("finish", () => {
writeStream.close();
console.log("File downloaded");
resolve();
});
writeStream.on("error", (err) => {
console.log(err);
reject(err);
});
});
});
return promise;
};
Secondly, you are using Promise.all which awaits for all the promises in parallel.
You can replace that code snippet with:
const req = https.get(URL_TO_PARSE, async (res) => {
let xml = '';
res.on('data', (stream) => {
xml = xml + stream;
});
res.on('end', () => {
parser.parseString(xml, async (err, result) => {
if (err) {
console.log(err);
} else {
let items = result.rss.channel[0].item;
for(const item of items) {
let title = item.title[0];
let enclosure = item.enclosure[0];
let url = enclosure.$.url;
let filepath = `./${title}`;
console.log(`Downloading ${title} to ${filepath}`);
await download_audio_file(url, filepath);
}
}
});
});
});
Notice how I replaced the Promise.all with for(const item of items)