YTMP3 API with ytdl-core.md

import ytdl from 'ytdl-core';

// ....
 
fastify.get('/ytmp3', async (req, res) => {
        let { id, lang } = req.query;
        if (!ytdl.validateID(id)) {
            res.send({
                result: false,
                error: "Invalid ID"
            })
        }
        try {
            let ytdata = await ytdl.getInfo(`https://youtube.com/watch?v=${id}`, { lang: lang ?? 'en' })
            let audio = ytdata.player_response.streamingData.adaptiveFormats.filter((d) => d.mimeType.startsWith("audio"))
            res.send({
                result: true,
                audio
            })
        } catch (err) {
            res.send({
                result: false,
                error: String(err)
            })
        }
    })

Some notes:

• lang ?? 'en' can lead to the language being empty, you can use || instead.
• You can use ytdl.validateURL to accept both URLs and IDs.
• You can remove the fastify.get and res.send parts to make it usable for any http library.