YTDJ/js/main.js

// Loads the IFrame Player API code asynchronously.
let tag = document.createElement('script');
tag.src = 'https://www.youtube.com/iframe_api';
let firstScriptTag = document.getElementsByTagName('script')[0];
firstScriptTag.parentNode.insertBefore(tag, firstScriptTag);

//THE DJ CROSSFADER!!!
let crossfader = document.querySelector('#crossfader');

class player {
  trackID;
  player;
  crossfaderCoef;

  constructor(id) {
    this.id = id;
    this.iframe = document.querySelector('#'+this.id);

    this.node = this.iframe.parentNode;
    this.volume = this.node.querySelector('.volume-slider').value;
    this.volSliderVal = this.node.querySelector('.volume-slider-value');
    this.volVal = this.node.querySelector('.volume-value')
    this.volSliderVal.innerHTML = this.volume + '%';
    this.loadButton = this.node.querySelector('.load-button');
    this.speedSlider = this.node.querySelector('.speed-slider');
    this.speedSlider.nextElementSibling.querySelector('.speed-value').innerHTML = this.speedSlider.value;
  }

  init(trackID) {
    this.trackID = trackID;
    let src = `https://www.youtube-nocookie.com/embed/${trackID}?disablekb=1&enablejsapi=1&playsinline=1&autoplay=0&rel=0&modestbranding=1&iv_load_policy=3&version=3`;
    this.iframe.setAttribute('src', src);
    this.player = new YT.Player(this.id, {
      events: {
        'onReady': this.onPlayerReady.bind(this),
        'onStateChange': this.onPlayerStateChange.bind(this),
        'onError': this.onPlayerError.bind(this)
      }
    });
  }
  onPlayerReady(e) {
    this.player.setVolume(this.volume);

    this.node.querySelector('.volume-slider').addEventListener('input', (e) => {
      this.volume = e.target.value;
      this.volSliderVal.innerHTML = this.volume + '%';
      this.volumeUpdate();
    });

    this.loadButton.addEventListener('click', () => {
      let url = prompt('Enter a YouTube URL (track or playlist):', 'https://www.youtube.com/watch?v=' + this.trackID);

      if (url) {
        let newTrackID = get_video_id(url);
        let newPlaylistID = get_playlist_id(url);

        if (newPlaylistID[0] != 0) {
          console.log('playlistid to load: ' + newPlaylistID);
          this.loadPlaylist(newPlaylistID);
        } else if (newTrackID != 0) {
          console.log('track to load: ' + newTrackID);
          this.load(newTrackID);
        } else {
          console.log('Nothing to load!');
        }

      }
    });

    this.speedSlider.addEventListener('input', (e) => {
      this.speedSlider.nextElementSibling.querySelector('.speed-value').innerHTML = e.target.value;
      this.player.setPlaybackRate(Number(e.target.value));
    });

    this.volumeUpdate();
  }

  onPlayerStateChange(e) {
    console.log(this.id + ' state change: ' + e.data);
  }

  onPlayerError(e) {
    console.log(this.id + ' - Error: ' + e.data);
  }

  load(trackID) {
    this.player.loadVideoById(trackID);
  }

  loadPlaylist(playlistID) {
    //First element should be the playlist ID, second element the index of the video to play
    let list = playlistID[0];
    let index = playlistID[1];

    this.player.loadPlaylist({
      list: list,
      listType: 'playlist',
      index: index
    });
  }

  volumeUpdate() {
    let outputVolume = Math.round(this.volume * this.crossfaderCoef);
    this.player.setVolume(outputVolume);

    this.volVal.innerHTML = outputVolume + '%';

    let boxShadowStyle = '0 0 3em #ddbddd'
    this.iframe.style.boxShadow = boxShadowStyle + componentToHex(Math.round(this.crossfaderCoef*255));
  }
}


let playerA = new player('playerA');
let playerB = new player('playerB');


function onYouTubeIframeAPIReady() {
  playerA.init('anWaxGNDRJ4')
  playerB.init('PhEuAuhH418');
}

calcCrossfaderCoefs(crossfader.value);

crossfader.addEventListener('input', (e) => {
  //Makes the slider stick on the middle
  if (Math.abs(crossfader.value - 500) < 15) {
    crossfader.value = 500;
  }

  calcCrossfaderCoefs(crossfader.value);

  playerA.volumeUpdate();
  playerB.volumeUpdate();

  // updateCrossfader(crossfader.value);
});

function calcCrossfaderCoefs(input) {
  let normVal = input / 1000;

  //Classic 'transition' curve
  let coefB = Math.min(normVal*2, 1);
  let coefA = Math.min((1-normVal)*2, 1);

  //Cheap smooth curve
  // let coefB = normVal ** 2;
  // let coefA = (1 - normVal) ** 2;

  //Amplitude-preserving curve (but not power)
  // let coefB = (normVal ** 2) * (3 - 2 * normVal);
  // let coefA = 1 - coefB;

  playerA.crossfaderCoef = coefA;
  playerB.crossfaderCoef = coefB;
}


// From https://stackoverflow.com/a/55616161/14182148
function get_playlist_id(url) {
    let VID_REGEX = /^.*(youtu.be\/|v\/|u\/\w\/|embed\/|watch\?v=|\&v=)([^#\&\?]*).*/
    let regPlaylist = /[?&]list=([^#\&\?]+)/;
    let regIndex = /[?&]index=([^#]+)/;
    let match = url.match(regPlaylist);
    let matchIndex = url.match(regIndex);
    let index = 0;
    if (matchIndex != null) {
      index = matchIndex[1] - 1;
    }
    if (match != null) {
      return [match[1], index];
    } else {
      return [0,0];
    }
}

function get_video_id(url) { //originally 'video_id_from_playlist'
    let VID_REGEX = /^.*(youtu.be\/|v\/|u\/\w\/|embed\/|watch\?v=|\&v=)([^#\&\?]*).*/
    let video_id = url.match(VID_REGEX);
    if (video_id != null) {
      return video_id[2];
    } else {
      return 0;
    }
}

// From https://thomaspark.co/projects/needledrop/ by Thomas Park
// function getYouTubeID(url){
//   url = url.split(/(vi\/|v=|\/v\/|youtu\.be\/|\/embed\/)/);
//   return (url[2] !== undefined) ? url[2].split(/[^0-9a-z_\-]/i)[0] : false;
// }

// function get_video_id(url) {
//     url = url.split(/(vi\/|v=|\/v\/|youtu\.be\/|\/embed\/)/);
//     return (url[2] !== undefined) ? url[2].split(/[^0-9a-z_\-]/i)[0] : url[0];
// }

function componentToHex(c) {
  var hex = c.toString(16);
  return hex.length == 1 ? "0" + hex : hex;
}

// Thumbnails: https://i1.ytimg.com/vi/{trackID}/mqdefault.jpg