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YoutubePlayBack

Have you ever closed a YouTube video by accident, or have you gone to another one and when you come back the video starts from 0? With this extension it won't happen anymore

当前为 2024-02-18 提交的版本，查看 最新版本。

// ==UserScript==
// @license MIT
// @name         YoutubePlayBack
// @namespace    http://tampermonkey.net/
// @version      1.3
// @description  Have you ever closed a YouTube video by accident, or have you gone to another one and when you come back the video starts from 0? With this extension it won't happen anymore
// @author       Costin Alexandru Sandu
// @match        https://www.youtube.com/watch*
// @icon         https://tse4.mm.bing.net/th/id/OIG3.UOFNuEtdysdoeX0tMsVU?pid=ImgGn
// @grant        none
// ==/UserScript==

(function () {
  'strict'
  var configData = {
    savedProgressAlreadySet: false,
    savingInterval: 1500,
    currentVideoId: null
  }

  function executeFnInPageContext(fn) {
    const fnStringified = fn.toString()
    return window.eval('(' + fnStringified + ')' + '()')
  }

  function getVideoCurrentTime() {
    const currentTime = executeFnInPageContext(() => {
      const player = document.querySelector('#movie_player')
      return player.getCurrentTime()
    })
    return currentTime
  }

  function getVideoId() {
    if (configData.currentVideoId) {
      return configData.currentVideoId
    }
    const id = executeFnInPageContext(() => {
      const player = document.querySelector('#movie_player')
      return player.getVideoData().video_id
    })
    return id
  }

  function playerExists() {
    const exists = executeFnInPageContext(() => {
      const player = document.querySelector('#movie_player')
      return Boolean(player)
    })
    return exists
  }

  function setVideoProgress(progress) {
    window.eval('var progress =' + progress)
    executeFnInPageContext(() => {
      const player = document.querySelector('#movie_player')
      player.seekTo(window.progress)
    })
    window.eval('delete progress')
  }

  function saveVideoProgress() {
    const videoProgress = getVideoCurrentTime()
    const videoId = getVideoId()

    configData.currentVideoId = videoId
    window.localStorage.setItem(videoId, videoProgress)
  }

  function getSavedVideoProgress() {
    const videoId = getVideoId()
    const savedVideoProgress = window.localStorage.getItem(videoId)

    return savedVideoProgress
  }

  function setSavedProgress() {
    const savedProgress = getSavedVideoProgress();
    setVideoProgress(savedProgress)
    configData.savedProgressAlreadySet = true
  }

  // code ref: https://stackoverflow.com/questions/5525071/how-to-wait-until-an-element-exists
  function waitForElm(selector) {
    return new Promise(resolve => {
        if (document.querySelector(selector)) {
            return resolve(document.querySelector(selector));
        }

        const observer = new MutationObserver(mutations => {
            if (document.querySelector(selector)) {
                observer.disconnect();
                resolve(document.querySelector(selector));
            }
        });

        // If you get "parameter 1 is not of type 'Node'" error, see https://stackoverflow.com/a/77855838/492336
        observer.observe(document.body, {
            childList: true,
            subtree: true
        });
    });
	}

  async function onPlayerElementExist(callback) {
    await waitForElm('#movie_player')
    callback()
  }

  function isReadyToSetSavedProgress() {
    return !configData.savedProgressAlreadySet && playerExists() && getSavedVideoProgress()
  }

  function initialize() {
    onPlayerElementExist(() => {
      if (isReadyToSetSavedProgress()) {
      	setSavedProgress()
    	}
    })

    setInterval(saveVideoProgress, configData.savingInterval)
  }

  initialize()
})();