var nAgt = navigator.userAgent;
var fullVersion  = ''+parseFloat(navigator.appVersion); 
var majorVersion = parseInt(navigator.appVersion,10);

var IE, FireFox, Chrome, Safari = false;
var validbrowser = false;
var IEMin = 7;
var FFMin = 5;
var ChromeMin = 10;
var SafariMin = 5;

// In MSIE, the true version is after "MSIE" in userAgent
if ((verOffset=nAgt.indexOf("MSIE"))!=-1) {
	IE = true;
	fullVersion = nAgt.substring(verOffset+5);
}
// IE 11 has different User Agent string 
// e.g. Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv:11.0) like Gecko

else if ((verOffset=nAgt.indexOf("rv:"))!=-1) {
	IE = true;
	fullVersion = nAgt.substring(verOffset+3);
}
// In Chrome, the true version is after "Chrome" 
else if ((verOffset=nAgt.indexOf("Chrome"))!=-1) {
	Chrome = true;
	fullVersion = nAgt.substring(verOffset+7);
}
// In Safari, the true version is after "Safari" or after "Version" 
else if ((verOffset=nAgt.indexOf("Safari"))!=-1) {
	Safari = true;
	fullVersion = nAgt.substring(verOffset+7);
	if ((verOffset=nAgt.indexOf("Version"))!=-1) 
		fullVersion = nAgt.substring(verOffset+8);
}
// In Firefox, the true version is after "Firefox" 
else if ((verOffset=nAgt.indexOf("Firefox"))!=-1) {
	FireFox = true;
	fullVersion = nAgt.substring(verOffset+8);
}

// trim the fullVersion string at semicolon/space if present
if ((ix=fullVersion.indexOf(";"))!=-1)
   fullVersion=fullVersion.substring(0,ix);
if ((ix=fullVersion.indexOf(" "))!=-1)
   fullVersion=fullVersion.substring(0,ix);

majorVersion = parseInt(''+fullVersion,10);
if (isNaN(majorVersion)) {
 fullVersion  = ''+parseFloat(navigator.appVersion); 
 majorVersion = parseInt(navigator.appVersion,10);
}
 
// make sure version is valid
if (IE && majorVersion >= IEMin)
	validbrowser = true;
else if (FireFox && majorVersion >= FFMin)
	validbrowser = true;
else if (Chrome && majorVersion >= ChromeMin)
	validbrowser = true;
else if (Safari && majorVersion >= SafariMin)
	validbrowser = true;

if (!validbrowser) {
	document.location="invalidBrowser.jsp";
}