前端JS实现全屏和退出全屏的效果

// 进入全屏和退出全屏的点击事件
      function fscreen() {
        var el = document.documentElement
        var isFullscreen = document.fullScreen || document.mozFullScreen || document.webkitIsFullScreen
        if (!isFullscreen) {
          //进入全屏
          ;
          (el.requestFullscreen && el.requestFullscreen()) ||
          (el.mozRequestFullScreen && el.mozRequestFullScreen()) ||
          (el.webkitRequestFullscreen && el.webkitRequestFullscreen()) ||
          (el.msRequestFullscreen && el.msRequestFullscreen())
        } else {
          //退出全屏
          document.exitFullscreen ?
            document.exitFullscreen() :
            document.mozCancelFullScreen ?
            document.mozCancelFullScreen() :
            document.webkitExitFullscreen ?
            document.webkitExitFullscreen() :
            ''
        }
      }