js實現全屏和退出全屏

1.按F11實現的全屏，用api不能退出；用api實現的全屏，可以用api退出全屏；
所以這裏監聽F11事件並阻止事件， 同時執行自己寫的全屏函數
window.addEventListener('keydown',e => {
  e = e || window.event
  if (e.keyCode===122) {
    e.preventDefault()
    this.launchFullscreen()
  }
})

2.全屏按鈕則直接執行這個全屏函數

launchFullscreen() {
    let isFullscreen = document.fullScreen || document.mozFullScreen || document.webkitIsFullScreen;
    if(!isFullscreen){
      if (window.ActiveXObject) {
        var WsShell = new ActiveXObject('WScript.Shell')
        WsShell.SendKeys('{F11}');
      }else{
        let el = document.documentElement
        let rfs = el.requestFullScreen || el.webkitRequestFullScreen || el.mozRequestFullScreen || el.msRequestFullscreen
        if (rfs) { // typeof rfs != "undefined" && rfs
          rfs.call(el)
        }
      }
    }else{
      document.exitFullscreen ? document.exitFullscreen() :
      document.mozCancelFullScreen ? document.mozCancelFullScreen() :
      document.webkitExitFullscreen ? document.webkitExitFullscreen() : '';
    }
  },