Writing a music command for your discord.js bot (Updated March 2020)

// your index.js should look similar to this:
const { CommandoClient } = require('discord.js-commando');
const { Structures } = require('discord.js');
const path = require('path');
const { prefix, token } = require('./config.json');
// It's vital this is before the initiation of the client
Structures.extend('Guild', Guild => {
  class MusicGuild extends Guild {
    constructor(client, data) {
      super(client, data);
      this.musicData = {
        queue: [],
        isPlaying: false,
        volume: 1,
        songDispatcher: null
      };
    }
  }
  return MusicGuild;
});
const client = new CommandoClient({
  commandPrefix: prefix,
  owner: 'your-discord-user-id',
  unknownCommandResponse: false
});

client.registry
  .registerDefaultTypes()
  .registerGroups([
    ['music', 'Music Command Group']
  ])
  .registerDefaultGroups()
  .registerDefaultCommands()
  .registerCommandsIn(path.join(__dirname, 'commands'));

client.once('ready', () => {
  console.log('Ready!');
});

client.login(token);

const { Command } = require('discord.js-commando');
const { MessageEmbed } = require('discord.js');
const Youtube = require('simple-youtube-api');
const ytdl = require('ytdl-core');
const { youtubeAPI } = require('../../config.json');
const youtube = new Youtube(youtubeAPI);

module.exports = class PlayCommand extends Command {
  constructor(client) {
    super(client, {
      name: 'play', 
      memberName: 'play',
      group: 'music', // this means the folder the file is inside
      description: 'Play any song or playlist from youtube',
      guildOnly: true, // make this command available only in servers not dm's
      clientPermissions: ['SPEAK', 'CONNECT'],
      args: [
        {
          key: 'query', // here we name the variable that will hold the input
          prompt: 'What song would you like to listen to?', // send this msg if
          // the user hasn't provided any arg or if the arg was not a string
          type: 'string',
          validate: query => query.length > 0 && query.length < 200 
        }
      ]
    });
  }

  async run(message, { query }) {
    // don't let users run this command if they are not in a voice channel
    var voiceChannel = message.member.voice.channel;
    if (!voiceChannel) return message.say('Join a channel and try again');

!play Darude Sandstorm
!play https://www.youtube.com/watch?v=y6120QOlsfU (and other url kinds)
!play https://www.youtube.com/playlist?list=PLuUrokoVSxlfUJuJB_D8j_wsFR4exaEmy

    if (
      query.match(
        /^(?!.*\?.*\bv=)https:\/\/www\.youtube\.com\/.*\?.*\blist=.*$/
      )
    ) {
      try {
        const playlist = await youtube.getPlaylist(query); // get playlist data 
        const videosObj = await playlist.getVideos(); // songs data object
        //const videos = Object.entries(videosObj); // turn the object to array
        // iterate through the videos array and make a song object out of each vid
        for (let i = 0; i < videosObj.length; i++) { 
          const video = await videosObj[i].fetch();

          const url = `https://www.youtube.com/watch?v=${video.raw.id}`;
          const title = video.raw.snippet.title;
          let duration = this.formatDuration(video.duration);
          const thumbnail = video.thumbnails.high.url;
          if (duration == '00:00') duration = 'Live Stream';
          const song = {
            url,
            title,
            duration,
            thumbnail,
            voiceChannel
          };

          message.guild.musicData.queue.push(song); // if you remember, the queue lives in the guild object so each server has its own queue

        }
        if (message.guild.musicData.isPlaying == false) { // if nothing is playing
          message.guild.musicData.isPlaying = true;
          return this.playSong(message.guild.musicData.queue, message); // play the playlist
        } else if (message.guild.musicData.isPlaying == true) { // if something is already playing
          return message.say(
            `Playlist - :musical_note:  ${playlist.title} :musical_note: has been added to queue`
          );
        }
      } catch (err) {
        console.error(err);
        return message.say('Playlist is either private or it does not exist');
      }
    }

    if (query.match(/^(http(s)?:\/\/)?((w){3}.)?youtu(be|.be)?(\.com)?\/.+/)) {
      const url = query; // temp variable
      try {
        query = query
          .replace(/(>|<)/gi, '')
          .split(/(vi\/|v=|\/v\/|youtu\.be\/|\/embed\/)/);
        const id = query[2].split(/[^0-9a-z_\-]/i)[0];
        const video = await youtube.getVideoByID(id);
        const title = video.title;
        let duration = this.formatDuration(video.duration);
        const thumbnail = video.thumbnails.high.url;
        if (duration == '00:00') duration = 'Live Stream';
        const song = {
          url,
          title,
          duration,
          thumbnail,
          voiceChannel
        };
        message.guild.musicData.queue.push(song);
        if (
          message.guild.musicData.isPlaying == false ||
          typeof message.guild.musicData.isPlaying == 'undefined'
        ) {
          message.guild.musicData.isPlaying = true;
          return this.playSong(message.guild.musicData.queue, message);
        } else if (message.guild.musicData.isPlaying == true) {
          return message.say(`${song.title} added to queue`);
        }
      } catch (err) {
        console.error(err);
        return message.say('Something went wrong, please try again later');
      }
    }

    try {
      // search for the song and get 5 results back
      const videos = await youtube.searchVideos(query, 5);
      if (videos.length < 5) {
        return message.say(
          `I had some trouble finding what you were looking for, please try again or be more specific`
        );
      }
      const vidNameArr = [];
      // create an array that contains the result titles
      for (let i = 0; i < videos.length; i++) {
        vidNameArr.push(`${i + 1}: ${videos[i].title}`);
      }
      vidNameArr.push('exit'); // push 'exit' string as it will be an option
      // create and display an embed which will present the user the 5 results
      // so he can choose his desired result
      const embed = new MessageEmbed()
        .setColor('#e9f931')
        .setTitle('Choose a song by commenting a number between 1 and 5')
        .addField('Song 1', vidNameArr[0])
        .addField('Song 2', vidNameArr[1])
        .addField('Song 3', vidNameArr[2])
        .addField('Song 4', vidNameArr[3])
        .addField('Song 5', vidNameArr[4])
        .addField('Exit', 'exit'); // user can reply with 'exit' if none matches
      var songEmbed = await message.say({ embed });
      try {
        // wait 1 minute for the user's response
        var response = await message.channel.awaitMessages(
          msg => (msg.content > 0 && msg.content < 6) || msg.content === 'exit',
          {
            max: 1,
            maxProcessed: 1,
            time: 60000,
            errors: ['time']
          }
        );
        // assign videoIndex to user's response
        var videoIndex = parseInt(response.first().content);
      } catch (err) {
        console.error(err);
        songEmbed.delete();
        return message.say(
          'Please try again and enter a number between 1 and 5 or exit'
        );
      }
      // if the user responded with 'exit', cancel the command
      if (response.first().content === 'exit') return songEmbed.delete();
      try {
        // get video data from the API
        var video = await youtube.getVideoByID(videos[videoIndex - 1].id);
      } catch (err) {
        console.error(err);
        songEmbed.delete();
        return message.say(
          'An error has occured when trying to get the video ID from youtube'
        );
      }
      const url = `https://www.youtube.com/watch?v=${video.raw.id}`;
      const title = video.title;
      let duration = this.formatDuration(video.duration);
      const thumbnail = video.thumbnails.high.url;
        if (duration == '00:00') duration = 'Live Stream';
        const song = {
          url,
          title,
          duration,
          thumbnail,
          voiceChannel
        };

        message.guild.musicData.queue.push(song);

        if (message.guild.musicData.isPlaying == false) {
          message.guild.musicData.isPlaying = true;
          songEmbed.delete(); // delete the selection embed
          this.playSong(message.guild.musicData.queue, message);
        } else if (message.guild.musicData.isPlaying == true) {
          songEmbed.delete();
          // add the song to queue if one is already playing
          return message.say(`${song.title} added to queue`);
        }
    } catch (err) {
      // if something went wrong when calling the api:
      console.error(err);
      if (songEmbed) {
        songEmbed.delete();
      }
      return message.say(
        'Something went wrong with searching the video you requested :('
      );
    }
  }

// this is inside the PlayCommand class
  playSong(queue, message) {
    let voiceChannel;
    queue[0].voiceChannel
      .join() // join the user's voice channel
      .then(connection => {
        const dispatcher = connection
          .play(
            ytdl(queue[0].url, { // pass the url to .ytdl()
              quality: 'highestaudio',
              // download part of the song before playing it
              // helps reduces stuttering
              highWaterMark: 1024 * 1024 * 10
            })
          )
          .on('start', () => {
            // the following line is essential to other commands like skip
            message.guild.musicData.songDispatcher = dispatcher;
            dispatcher.setVolume(message.guild.musicData.volume);
            voiceChannel = queue[0].voiceChannel;
            // display the current playing song as a nice little embed
            const videoEmbed = new MessageEmbed()
              .setThumbnail(queue[0].thumbnail) // song thumbnail
              .setColor('#e9f931')
              .addField('Now Playing:', queue[0].title)
              .addField('Duration:', queue[0].duration);
            // also display next song title, if there is one in queue
            if (queue[1]) videoEmbed.addField('Next Song:', queue[1].title);
            message.say(videoEmbed); // send the embed to chat
            return queue.shift(); //  dequeue the song
          })
          .on('finish', () => { // this event fires when the song has ended
            if (queue.length >= 1) { // if there are more songs in queue
              return this.playSong(queue, message); // continue playing
            } else { // else if there are no more songs in queue
              message.guild.musicData.isPlaying = false;
              return voiceChannel.leave(); // leave the voice channel
            }
          })
          .on('error', e => {
            message.say('Cannot play song');
            message.guild.musicData.queue.length = 0;
            message.guild.musicData.isPlaying = false;
            message.guild.musicData.nowPlaying = null;
            console.error(e);
            return voiceChannel.leave();
          });
      })
      .catch(e => {
        console.error(e);
        return voiceChannel.leave();
      });
  }

  formatDuration(durationObj) {
    const duration = `${durationObj.hours ? durationObj.hours + ':' : ''}${
      durationObj.minutes ? durationObj.minutes : '00'
    }:${
      durationObj.seconds < 10
        ? '0' + durationObj.seconds
        : durationObj.seconds
        ? durationObj.seconds
        : '00'
    }`;
    return duration;
  }