How to allow web application to run only in IE Browser?

See more:

C#

ASP.NET

Javascript

IE11

I want to allow web app only in IE Browser. On selecting Chrome the Application will exit after the alert script. But in IE 11 the alert message comes. It works for the lower version IE Browsers.

My code is as below:
<script language="javascript" type="text/javascript">


window.onload = function() {
var nAgt = navigator.userAgent;
alert(nAgt.indexOf("MSIE"));
alert(nAgt.indexOf("Firefox"));
if ((verOffset = nAgt.indexOf("MSIE")) == -1 && (verOffset = nAgt.indexOf("Firefox")) == -1) {
alert("This application runs only in IE and Mozilla");
window.open('', '_self', '');
window.close();
}
}
</script>