js 当前窗口全屏

// 请求全屏
function requestFullScreen() {
  var elem = document.documentElement;
  if (elem.requestFullscreen) {
    elem.requestFullscreen();
  } else if (elem.mozRequestFullScreen) { // Firefox
    elem.mozRequestFullScreen();
  } else if (elem.webkitRequestFullscreen) { // Chrome, Safari and Opera
    elem.webkitRequestFullscreen();
  } else if (elem.msRequestFullscreen) { // IE/Edge
    elem.msRequestFullscreen();
  }
}

// 退出全屏
function exitFullScreen() {
  if (document.exitFullscreen) {
    document.exitFullscreen();
  } else if (document.mozCancelFullScreen) { // Firefox
    document.mozCancelFullScreen();
  } else if (document.webkitExitFullscreen) { // Chrome, Safari and Opera
    document.webkitExitFullscreen();
  } else if (document.msExitFullscreen) { // IE/Edge
    document.msExitFullscreen();
  }
}