JS浏览器全屏

<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<input id="Button1" type="button" value="开启全屏" onclick="kaishi()" />  
		<input id="Button2" type="button" value="关闭全屏" onclick="guanbi()" />  
	</body>
	<script>
//		 开始全屏
    function kaishi()  
    {  
        var docElm = document.documentElement;  
        //W3C   
        if (docElm.requestFullscreen) {  
            docElm.requestFullscreen();  
        }  
            //FireFox   
        else if (docElm.mozRequestFullScreen) {  
            docElm.mozRequestFullScreen();  
        }  
            //Chrome等   
        else if (docElm.webkitRequestFullScreen) {  
            docElm.webkitRequestFullScreen();  
        }  
            //IE11   
        else if (elem.msRequestFullscreen) {  
            elem.msRequestFullscreen();  
        }  
    }  
  
//  退出全屏
    function guanbi() {  
  
  
        if (document.exitFullscreen) {  
            document.exitFullscreen();  
        }  
        else if (document.mozCancelFullScreen) {  
            document.mozCancelFullScreen();  
        }  
        else if (document.webkitCancelFullScreen) {  
            document.webkitCancelFullScreen();  
        }  
        else if (document.msExitFullscreen) {  
            document.msExitFullscreen();  
        }  
    }  
  
  
//事件监听
//
//  document.addEventListener("fullscreenchange", function () {  
// 
//      fullscreenState.innerHTML = (document.fullscreen) ? "" : "not ";  
//      alert("1531");
//  }, false);  
//    
//  document.addEventListener("mozfullscreenchange", function () {  
//       
//      fullscreenState.innerHTML = (document.mozFullScreen) ? "" : "not ";  
//  }, false);  
//   
//  document.addEventListener("webkitfullscreenchange", function () {  
//        
//      fullscreenState.innerHTML = (document.webkitIsFullScreen) ? "" : "not ";  
//  }, false);  
//    
//  document.addEventListener("msfullscreenchange", function () {  
//        
//      fullscreenState.innerHTML = (document.msFullscreenElement) ? "" : "not ";  
//  }, false);  
  
	</script>
</html>