Shuffle YouTube Playlist (via Apps Script)

shuffle_youtube_playlist.js

/**
 * @fileoverview Shuffles a YouTube playlist on every run.
 *
 * Note: currently this only supports up to 50 videos, but you can extend it to
 * support more by combining the pages into one.
 *
 * This code is meant to be run on Google Apps Script. To get started with
 * YouTube API on Apps Script and add the YouTube service, read this article:
 * https://developers.google.com/apps-script/guides/services/advanced
 */

/** @const {string} Playlist id. Copy from the URL of the playlist (&list=). */
const PLAYLIST_ID = '';

/**
 * Shuffles a YouTube playlist videos.
 *
 * Call this function to start the process.
 * Retrieves all videos (up to 50) on the given playlist id into an array.
 * Shuffles the array in a random order.
 * Updates the YouTube playlist with the new shuffled video positions.
 */
function main() {
  const playlistItems = YouTube.PlaylistItems.list(
    ['id', 'snippet'],
    {
      'playlistId': PLAYLIST_ID,
      'maxResults': 50,
    });

  // TODO(reader): the code only handles first 50 videos, as this is the max
  // result from YouTube API without pagination. If your playlist is longer,
  // you may need to request all the other pages to have a complete list of
  // videos when calling getItems();
  let videos = playlistItems.getItems();
  videos = shuffleArray(videos);

  videos.forEach((video, arrayIndex) => {
    const previousPosition = video.snippet.position;
    video.snippet.position = arrayIndex;

    YouTube.PlaylistItems.update(
      {
        'id': video.id,
        'snippet': {
          'playlistId': PLAYLIST_ID,
          'position': video.snippet.position,
          'resourceId': {
            'kind': video.snippet.resourceId.kind,
            'videoId': video.snippet.resourceId.videoId,
          },
        },
      },
      ['snippet'],
    );

    console.log(
      `video id: ${video.snippet.resourceId.videoId}, ` +
      `before position: ${previousPosition}, ` +
      `after position: ${video.snippet.position}`
    );
  });
}

/**
 * Randomly shuffles a given array.
 * @param {!Array<T>} array Array to shuffle.
 * @return {!Array<T>} Same array but with elements shuffled in order.
 */
function shuffleArray(array) {
  let currentIndex = array.length;
  let randomIndex;

  while (currentIndex != 0) {
    randomIndex = Math.floor(Math.random() * currentIndex);
    currentIndex--;

    const currentElement = array[currentIndex];
    const randomElement = array[randomIndex];

    array[currentIndex] = randomElement;
    array[randomIndex] = currentElement;
  }

  return array;
}