full music bot written in eris. at this moment it only supports playing in one guild at a time, but this can be fixed very easily.

quark_music.js

'use strict';

const Eris = require("eris");
const ytdl = require('ytdl-core');

var bot = new Eris.CommandClient("token", {}, {
    description: "The Quantum MusicBot.",
    owner: "Gus",
    prefix: "q!"
});

var connections = [];
var queue = [];
var now = {};

function playSomething() {
    let temp = queue.shift();
    if (connections[now.vc]) {
        if (connections[now.vc].playing) {
            queue.unshift(temp);
            return;
        }
    }
    now = temp;
    bot.joinVoiceChannel(now.vc).catch((err) => {
        bot.createMessage(now.txt, "Error joining voice channel: " + err.message);
    }).then((connection) => {
        connections[connection.channelID] = connection;
        if(connection.playing) {
            return "already playing, something went wrong";
        }
        let stream = ytdl(now.url, { audioonly: true });
        connection.playStream(stream);
        bot.createMessage(now.txt, `Playing **${now.name}**`);
        connection.once("end", () => {
            connection.stopPlaying();
            if (queue.length > 0) {
                playSomething();
            }
        });
    });
}

var playCmd = bot.registerCommand("play", (msg, args) => {
    if(args.length === 0) {
        return "Invalid input";
    }
    if(msg.member.voiceState === null) {
       return "You are not in a voice channel.";
    }
    var url = args[0].replace('<','').replace('>','');
    try {
        ytdl.getInfo(url, (err, info) => {
            if (!err) {
                queue.push({name: info.title, url: url, requestedBy: msg.member.id, vc: msg.member.voiceState.channelID, txt: msg.channel.id});
                bot.createMessage(msg.channel.id, "Added song to queue!");
                playSomething();
            } else {
                return "url is invalid or cannot be played";
            }
        });
    } catch (err) {
        return "that url is invalid, sorry";
    }

}, {
    description: "add a song to the queue",
    fullDescription: "add a song to the queue",
    usage: "<url>",
    serverOnly: true
});

var stopCmd = bot.registerCommand("stop", (msg, args) => {
    if(msg.member.voiceState === null) {
       return "You are not in a voice channel.";
    }
    try {
        connections[msg.member.voiceState.channelID].stopPlaying();
        connections[msg.member.voiceState.channelID].disconnect();
        delete connections[msg.member.voiceState.channelID];
        queue = [];
        return "all good ;)";
    } catch (err) {
        return "something went wrong";
    }
},{
    description: "stop the music",
    fullDescription: "stop the music",
    serverOnly: true
});

bot.registerCommand("list", (msg, args) => {
    return queue.length > 0 ? queue.map((q, i) => `${i+1}. ${q.name}`).join('\n') : "Queue is empty!";
}, {
    description: "get list of songs",
    serverOnly: true
});

bot.registerCommand("playing", (msg, args) => {
    return `Now Playing: **${now.name}**`;
}, {
    description: "get currently playing song",
    serverOnly: true
});

bot.registerCommand("ping", "Pong!", {
    description: "Pong!",
    fullDescription: "ping pong ping pong"
});

bot.on("ready", () => {
    console.log("Ready!");
});

bot.connect();