f11 全屏

function fullScreen() {

  var el = document.documentElement;

  var rfs = el.requestFullScreen || el.webkitRequestFullScreen || 

      el.mozRequestFullScreen || el.msRequestFullScreen;

  if(typeof rfs != "undefined" && rfs) {

    rfs.call(el);

  } else if(typeof window.ActiveXObject != "undefined") {

    //for IE，这里其实就是模拟了按下键盘的F11，使浏览器全屏

    var wscript = new ActiveXObject("WScript.Shell");

    if(wscript != null) {

        wscript.SendKeys("{F11}");

    }

  }
}

function exitFullScreen() {

  var el = document;

  var cfs = el.cancelFullScreen || el.webkitCancelFullScreen || 

      el.mozCancelFullScreen || el.exitFullScreen;

  if(typeof cfs != "undefined" && cfs) {

    cfs.call(el);

  } else if(typeof window.ActiveXObject != "undefined") {

    //for IE，这里和fullScreen相同，模拟按下F11键退出全屏

    var wscript = new ActiveXObject("WScript.Shell");

    if(wscript != null) {

        wscript.SendKeys("{F11}");

    }

  }
}