code: function toggleFullScreen() {
    /* Convenient renames */
    var docElem = document.documentElement;
    var doc = document;
  
    docElem.requestFullscreen =
        docElem.requestFullscreen ||
        docElem.msRequestFullscreen ||
        docElem.mozRequestFullScreen ||
        docElem.webkitRequestFullscreen.bind(docElem, Element.ALLOW_KEYBOARD_INPUT);
  
    doc.exitFullscreen =
        doc.exitFullscreen ||
        doc.msExitFullscreen ||
        doc.mozCancelFullScreen ||
        doc.webkitExitFullscreen;
  
    isFullScreen() ? doc.exitFullscreen() : docElem.requestFullscreen();
  }
docs: Toggle fullScreen mode on document element.
  Works on chrome (>= 15), firefox (>= 9), ie (>= 11), opera(>= 12.1), safari (>= 5).