Simple NodeJS function to convert .torrent files to magnet URIs

torrent-to-magnet.js

// This file is licensed under LGPLv3
// (c) teidesu 2020

const qs = require('querystring')
const crypto = require('crypto')
// https://gist.github.com/teidesu/a1eadf71ffd88166415e2ea8b94d3f3b
const bencode = require('./bencode')

function convert (file) {
    const data = bencode.decode(f)

    const infoHash = crypto.createHash('sha1').update(encode(data.info)).digest('hex')
    let params = {
        xt: `urn:btih:${infoHash}`,
        tr: []
    }
    
    if ('length' in data.info) {
        params.xl = data.info.length
    }
    if ('name' in data.info) {
        params.dn = data.info.name.toString('utf-8')
    }
    if ('announce' in data) {
        params.tr.push(data.announce.toString('utf-8'))
    }
    if ('announce-list' in data && Array.isArray(data['announce-list'])) {
        params.tr.push(...data['announce-list'].map(ann => ann.toString('utf-8')))
    }
    
    return 'magnet:?' + qs.stringify(params)
}

// usage:
console.log(convert(require('fs').readFileSync('lorem-ipsum.torrent')))

I tested using Bittorrent and it worked fine. I'm not sure what's wrong. 😥