AudioManager.js

///Singleton audio manager

class AudioManager{
  constructor(){
    this.sounds = {};
    this.queue = [];
    this.currentlyPlaying = null;
    this.currentAudio = null;
    this.paused = false;
  }
  
  //param object represents either a playlist or a single audio
  __play(object){
    let {playlist, delay, name, onEnded} = object;
    delay = (delay)? delay: 0;
    
    let audio = playlist[object.index++];
    this.currentlyPlaying = object;
    this.currentAudio = audio;
    audio.onended = () => {
      //current object done playing
      if(playlist.length >= object.index){
        //run onEnded callback when done playing object
        if(onEnded)
          onEnded();
        
        //reset index so you can play it again later
        object.index = 0;
        
        this.play(); //play next enqueued sound
        return ;
      }
      
      //play after delay
      setTimeout(() => {
        this.__play(object);
      }, delay);
    };
    audio.play();
    this.paused = false;
  }
  
  __getObject(data, onEnded){
    let {name, delay, playlist} = data;
    let obj;
    if(this.sounds.hasOwnProperty(name)){
      //fetch and update object
      obj = this.sounds[name];
      obj.delay = (delay)? delay: obj.delay;
      obj.onEnded = (onEnded)? onEnded: obj.onEnded;
      obj.playlist = (playlist)? playlist.map(src => new Audio(src)): obj.playlist;   
    } else{
      //create new object
      obj = {
        name,
        delay,
        onEnded,
        playlist: playlist.map(src => new Audio(src))
      };
      this.sounds[name] = obj;
    }
 
    return obj;
  }
  
  enqueue(data, onEnded=null){
    if(typeof data === 'string'){
      if(this.sounds.hasOwnProperty(data)){
        this.queue.push(this.sounds[data]);
      }else{
        this.enqueue({
          name: data, 
          delay: 0, 
          playlist: [data],
          onEnded
        });
      }
      return;
    }
    let obj = this.__getObject(data, onEnded);
    this.queue.push(obj);
  };
  
  
  clearQueue(){
    this.queue = [];
  }
    
  pause(){
    this.paused = true;
    this.currentAudio.pause();
  }
  
  play(data=null, onEnded = null){
    if(data === null){
      //play paused audio
      if(this.paused && this.currentAudio)
        this.currentAudio.play();
      //play next enqueued object
      else if(this.queue.length > 0){
        let obj = this.queue[0];
        this.queue = this.queue.slice(1);
        this.__play(obj);
      }
      return;
    }
    
    this.stop();  //stop playing what's playing
    this.clearQueue(); //clear queue
    
    //play sound
    if(typeof data === 'string'){
      // if data is name of stored sound
      if(this.sounds.hasOwnProperty(data)){
        //replace onEnded
        if(onEnded)
          this.sounds[data].onEnded = onEnded;
        this.__play(this.sounds[data]);        
      }else{
        // if data is path to file
        this.play({
          name: data,
          playlist: [data],
          delay: 0,
        },  onEnded);
      }
      return;
    } 

    let obj = this.__getObject(data, onEnded);
    this.enqueue(obj);
    this.play();
  }
  
  stop(){
    this.paused = false;
    this.currentAudio.stop();
    this.currentAudio = null;
    this.currentlyPlaying.index = 0;
    this.currentlyPlaying = null;
  }
}