YouTube.js/scripts/get-agents.mjs

import { fetch } from "undici";
import { gunzip } from "zlib";
import { dirname, resolve } from 'path';
import { fileURLToPath } from 'url';
import { writeFile } from "fs/promises";

(async () => {

const __dirname = dirname(fileURLToPath(import.meta.url));

const buf = await (await fetch('https://github.com/intoli/user-agents/blob/master/src/user-agents.json.gz?raw=true')).arrayBuffer();
const bytes = new Uint8Array(buf);

// Only get desktop and mobile agents
const allowed_agents = new Set([
    'desktop',
    'mobile',
])

const decompressed = await new Promise((resolve, reject) => {
    gunzip(bytes, (err, result) => {
        if (err) {
            reject(err);
        } else {
            resolve(result.buffer);
        }
    });
});

const contents = new TextDecoder().decode(decompressed);

const agents = JSON.parse(contents);

if (!Array.isArray(agents)) {
    throw new Error('Invalid user-agents.json');
}

const agentsByDevice = agents.reduce((acc, agent) => {
    const device = agent.deviceCategory;
    if (!allowed_agents.has(device)) 
        return acc;
    if (!acc[device]) {
        acc[device] = [];
    }
    // we dont want to massive of a list of agents for each device
    if (acc[device].length <= 25) acc[device].push(agent.userAgent);
    return acc;
}, {});

await writeFile(resolve(__dirname, '..', 'src', 'utils', 'user-agents.json'), JSON.stringify(agentsByDevice, null, 2));

})();