js控制浏览器是否全屏

        function fullScreen() {
            /*判断是否全屏*/
            var isFullscreen = document.fullScreenElement//W3C
                || document.msFullscreenElement //IE
                || document.mozFullScreenElement //火狐
                || document.webkitFullscreenElement //谷歌
                || false;
            if (!isFullscreen) {
                var el = document.documentElement;
                if (el.requestFullscreen) {
                    el.requestFullscreen();
                } else if (el.mozRequestFullScreen) {
                    el.mozRequestFullScreen();
                } else if (el.webkitRequestFullscreen) {
                    el.webkitRequestFullscreen();
                } else if (el.msRequestFullscreen) {
                    el.msRequestFullscreen();
                }
            } else {
                if (document.exitFullscreen) {
                    document.exitFullscreen();
                } else if (document.msExitFullscreen) {
                    document.msExitFullscreen();
                } else if (document.mozCancelFullScreen) {
                    document.mozCancelFullScreen();
                } else if (document.webkitCancelFullScreen) {
                    document.webkitCancelFullScreen();
                }
            }
        }