function FullScreen(){

          var el = $('html')[0];//要全屏的元素，如果要全页面全屏，建议使用html节点而不是body节点

          var isFullscreen=document.fullScreen||document.mozFullScreen||document.webkitIsFullScreen;

          if(!isFullscreen){//进入全屏,多重短路表达式

              (el.requestFullscreen&&el.requestFullscreen())||

              (el.mozRequestFullScreen&&el.mozRequestFullScreen())||

              (el.webkitRequestFullscreen&&el.webkitRequestFullscreen())||(el.msRequestFullscreen&&el.msRequestFullscreen());

          }else{    //退出全屏,三目运算符

              document.exitFullscreen?document.exitFullscreen():

              document.mozCancelFullScreen?document.mozCancelFullScreen():

              document.webkitExitFullscreen?document.webkitExitFullscreen():'';

          }

 }