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 internet explorer
var wscript = new activexobject(wscript.shell);
if (wscript != null) {
wscript.sendkeys({f11});
}
}
}