var _volumeNum = 1 // 音量值 var _speedNum = 1 // 速度值 var videoSrc = 'demo02.mp4' // 切換資源 window.onload = function () {  var myVideo = document.getElementById('myVideo')  var scSource = document.getElementById('sc')  var myVideoBody = { pause: true }  // 播放完成指令  myVideo.addEventListener('ended', function () {   scSource.src = videoSrc;   myVideo.load()   myVideo.play()  })  // 初始化  start() } // 獲取video function getVideo() {  var myVideo = document.getElementById('myVideo')  return myVideo } // 快進 function vforward(params) {  if (_speedNum >= 2) return  _speedNum = accAdd(_speedNum, 0.1)  console.log('vforward _speedNum: ', _speedNum)  getVideo().playbackRate = _speedNum } // 快退 function vbackward() {  if (_speedNum <= 0.5) return  var myVideo = getVideo()  _speedNum = accSub(_speedNum, 0.1)  console.log('vbackward _speedNum: ', _speedNum)  getVideo().playbackRate = _speedNum } // 頁面加載之后執行命令 function start() {  var myVideo = getVideo()  myVideo.volume = 1  myVideo.playbackRate = 1 } // 設置靜音 function setMuted() {  getVideo().muted = true } // 設置非靜音 function setNotMuted() {  getVideo().muted = false } // 播放 function vplay() {  console.log('vplay =>')  getVideo().play(); } // 暫停 function vstop() {  getVideo().pause(); } // 重播 function vrestart() {  getVideo().currentTime = 0  getVideo().play() } // 取消全屏 function cancelFull() {  screenfull.exit() } // 打開全屏 function openFull() {  getVideo().webkitRequestFullscreen() } // 音量 -- function reduceVolume() {  console.log('reduceVolume:: current volume: ', myVideo.volume) // 當前音量  getVideo().muted = false  if (_volumeNum <= 0) return  _volumeNum = accSub(_volumeNum, 0.1)  getVideo().volume = _volumeNum } // 音量 ++ function addVolume() {  console.log('addVolume:: current volume: ', myVideo.volume)  // 當前音量  getVideo().muted = false  if (_volumeNum >= 1) return  _volumeNum = accAdd(_volumeNum, 0.1)  getVideo().volume = _volumeNum }