图像/DIV 元素切换全屏

下面的代码是一个工作示例，当您单击图像时，它会全屏打开网页浏览器，但是我不知道如何使javascript在再次单击图像时切换全屏模式。

，然后在第二次单击同一图像时退出全屏模式。

.HTML：

    <h1>Click image to toogle fullscreen mode</h1>
    <img id="logo" src="http://i.imgur.com/lPZh57Y.png" alt="logo" />

JavaScript：

(function () {
    var viewFullScreen = document.getElementById("logo");
    if (viewFullScreen) {
       viewFullScreen.addEventListener("click", function () {
           var docElm = document.documentElement;
           if (docElm.requestFullscreen) {
               docElm.requestFullscreen();
           }
           else if (docElm.msRequestFullscreen) {
               docElm.msRequestFullscreen();
           }
           else if (docElm.mozRequestFullScreen) {
               docElm.mozRequestFullScreen();
           }
           else if (docElm.webkitRequestFullScreen) {
               docElm.webkitRequestFullScreen();
           }
       }, false);
   }
  var cancelFullScreen = document.getElementById("logoCONFLICT");
  if (cancelFullScreen) {
     cancelFullScreen.addEventListener("click", function () {
        if (document.exitFullscreen) {
            document.exitFullscreen();
        }
        else if (document.msExitFullscreen) {
            document.msExitFullscreen();
        }
        else if (document.mozCancelFullScreen) {
            document.mozCancelFullScreen();
        }
        else if (document.webkitCancelFullScreen) {
            document.webkitCancelFullScreen();
        }
     }, false);
  }   
})();