var _volumeNum = 1 // 音量值
 var _speedNum = 1 // 速度值
 var videoSrc = 'demo02.mp4' // 切换资源
 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()
 }
 // 获取video
 function getVideo() {
  var myVideo = document.getElementById('myVideo')
  return myVideo
 }
 // 快进
 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
 }
 // 页面加载之后执行命令
 function start() {
  var myVideo = getVideo()
  myVideo.volume = 1
  myVideo.playbackRate = 1
 }
 // 设置静音
 function setMuted() {
  getVideo().muted = true
 }
 // 设置非静音
 function setNotMuted() {
  getVideo().muted = false
 }
 // 播放
 function vplay() {
  console.log('vplay =>')
  getVideo().play();
 }
 // 暂停
 function vstop() {
  getVideo().pause();
 }
 // 重播
 function vrestart() {
  getVideo().currentTime = 0
  getVideo().play()
 }
 // 取消全屏
 function cancelFull() {
  screenfull.exit()
 }
 // 打开全屏
 function openFull() {
  getVideo().webkitRequestFullscreen()
 }
 // 音量 --
 function reduceVolume() {
  console.log('reduceVolume:: current volume: ', myVideo.volume) // 当前音量
  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)  // 当前音量
  getVideo().muted = false
  if (_volumeNum >= 1) return
  _volumeNum = accAdd(_volumeNum, 0.1)
  getVideo().volume = _volumeNum
 }