js模拟F11全屏功能

html部分：

js部分(isFllScreen是判断是否开了全屏用的变量)：

        fullScreen() {
            let docElm = document.documentElement;
            if (this.isFllScreen) {
                if (document.exitFullscreen) {
                    document.exitFullscreen();
                }
                else if (document.mozCancelFullScreen) {
                    document.mozCancelFullScreen();
                }
                else if (document.webkitCancelFullScreen) {
                    document.webkitCancelFullScreen();
                }
                else if (document.msExitFullscreen) {
                    document.msExitFullscreen();
                }
                this.isFllScreen = false
            } else {
                //W3C   
                if (docElm.requestFullscreen) {
                    docElm.requestFullscreen();
                }
                //FireFox   
                else if (docElm.mozRequestFullScreen) {
                    docElm.mozRequestFullScreen();
                }
                //Chrome等   
                else if (docElm.webkitRequestFullScreen) {
                    docElm.webkitRequestFullScreen();
                }
                this.isFllScreen = true
            }
        }

 效果：