1. handleFullScreen() {
    2.             let element = document.documentElement;
    3.             // 判断是否已经是全屏
    4.             // 如果是全屏，退出
    5.             if (this.fullscreen) {
    6.                 if (document.exitFullscreen) {
    7.                     document.exitFullscreen();
    8.                 } else if (document.webkitCancelFullScreen) {
    9.                     document.webkitCancelFullScreen();
    10.                 } else if (document.mozCancelFullScreen) {
    11.                     document.mozCancelFullScreen();
    12.                 } else if (document.msExitFullscreen) {
    13.                     document.msExitFullscreen();
    14.                 }
    15.                 console.log('已还原！');
    16.             } else { // 否则，进入全屏
    17.                 if (element.requestFullscreen) {
    18.                     element.requestFullscreen();
    19.                 } else if (element.webkitRequestFullScreen) {
    20.                     element.webkitRequestFullScreen();
    21.                 } else if (element.mozRequestFullScreen) {
    22.                     element.mozRequestFullScreen();
    23.                 } else if (element.msRequestFullscreen) {
    24.                     // IE11
    25.                     element.msRequestFullscreen();
    26.                 }
    27.                 console.log('已全屏！');
    28.             }
    29.             // 改变当前全屏状态
    30.             this.fullscreen = !this.fullscreen;
    31.         },