Access the spotify websocket api for real time updates about playback etc. Only works with an offical access token, third-party ones don't work.

spotify-ws.js

import axios from 'axios';
import WebSocket from 'ws';

/*
Use a spotify acces token from an offical source like open.spotify.com. You can obtain it by using the network inspector in your browser.
Third-party access token obtained via OAuth2 will not work because of an api limitation by spotify.
*/
const ACCESS_TOKEN = "";

const createWebSocketUrl = (accessToken) => `wss://dealer.spotify.com/?access_token=${accessToken}`;

const ws = new WebSocket(createWebSocketUrl(ACCESS_TOKEN));

const ping = () => {
    ws.send(JSON.stringify({
        type: "ping"
    }));
}

ws.on('open', function open() {
    console.log(new Date(), "Connected to spotify's websocket server!")
    ping();
    setInterval(ping, 15000);
});

ws.on('message', function incoming(message) {
  const jsonMessage = JSON.parse(message.toString());

  if ('headers' in jsonMessage && jsonMessage.headers['Spotify-Connection-Id'] ) {
    console.log(new Date(), "Received spotify connection id:\n", jsonMessage.headers['Spotify-Connection-Id'], "\n");
    
    // This will throw 401 if you're not using an offical access token.
    axios.put("https://api.spotify.com/v1/me/notifications/player", undefined, {
        params: {
            connection_id: jsonMessage.headers['Spotify-Connection-Id']
        },
        headers: {
            Authorization: `Bearer ${ACCESS_TOKEN}`
        }
    }).then(() => console.log(new Date(), "Sent subscription request to https://api.spotify.com/v1/me/notifications/player: \n"));
  } else {
     console.log(new Date(), jsonMessage);
  }
});