var BrowserDetect = {
	init: function () {
		this.browser = this.searchString(this.dataBrowser) || "An unknown browser";
		this.version = this.searchVersion(navigator.userAgent)
			|| this.searchVersion(navigator.appVersion)
			|| "an unknown version";
		this.OS = this.searchString(this.dataOS) || "an unknown OS";
	},
	searchString: function (data) {
		for (var i=0;i<data.length;i++)	{
			var dataString = data[i].string;
			var dataProp = data[i].prop;
			this.versionSearchString = data[i].versionSearch || data[i].identity;
			if (dataString) {
				if (dataString.indexOf(data[i].subString) != -1)
					return data[i].identity;
			}
			else if (dataProp)
				return data[i].identity;
		}
	},
	searchVersion: function (dataString) {
		var index = dataString.indexOf(this.versionSearchString);
		if (index == -1) return;
		return parseFloat(dataString.substring(index+this.versionSearchString.length+1));
	},
	dataBrowser: [
		{
			string: navigator.userAgent,
			subString: "Chrome",
			identity: "Chrome"},
		{
			string: navigator.vendor,
			subString: "Apple",
			identity: "Safari",
			versionSearch: "Version"},
		{
			string: navigator.userAgent,
			subString: "Firefox",
			identity: "Firefox"},
		{
			string: navigator.userAgent,
			subString: "MSIE",
			identity: "MSIE",
			versionSearch: "MSIE"}],
	dataOS : [
		{
			string: navigator.platform,
			subString: "Win",
			identity: "Windows"},
		{
			string: navigator.platform,
			subString: "Mac",
			identity: "Mac"},
		{
			string: navigator.platform,
			subString: "Linux",
			identity: "Linux"}]};
			
BrowserDetect.init();

var validBrowser="True";
switch(BrowserDetect.browser){
	case "MSIE":
		if(BrowserDetect.version < 6){
			alert(BrowserDetect.version);
			validBrowser="False";}
		break;
	case "Firefox":
		if(BrowserDetect.version < 2){
			validBrowser="False";}
		break;
	case "Chrome":
		if(BrowserDetect.version < 3){
			alert(BrowserDetect.version);
			validBrowser="False";}
		break;	
	case "Safari":
		if(BrowserDetect.version < 3){
			validBrowser="False";}
		break;
	default:
		validBrowser="False";}

if(validBrowser=="False") {
		alert("Your browser is not supported.  Supported browsers:\n\n - Microsoft Internet Explorer v6 or higher\n - Firefox v2 or higher\n - Safari v3 or higher\n - Chrome v3 or higher");}