function isPositiveInteger(val)
{
	if (isNaN(val)) return false;
	if (parseInt(val) != val) return false;
	if (val < 0) return false;
	
	return true;
}

function checkEmail (emailStr)
{

	/* The following variable tells the rest of the function whether or not
	to verify that the address ends in a two-letter country or well-known
	TLD.  1 means check it, 0 means don't. */
	
	var checkTLD=1;
	
	/* The following is the list of known TLDs that an e-mail address must end with. */
	
	var knownDomsPat=/^(com|net|org|edu|int|mil|gov|arpa|biz|aero|name|coop|info|pro|museum)$/;
	
	/* The following pattern is used to check if the entered e-mail address
	fits the user@domain format.  It also is used to separate the username
	from the domain. */
	
	var emailPat=/^(.+)@(.+)$/;
	
	/* The following string represents the pattern for matching all special
	characters.  We don't want to allow special characters in the address. 
	These characters include ( ) < > @ , ; : \ " . [ ] */
	
	var specialChars="\\(\\)><@,;:\\\\\\\"\\.\\[\\]";
	
	/* The following string represents the range of characters allowed in a 
	username or domainname.  It really states which chars aren't allowed.*/
	
	var validChars="\[^\\s" + specialChars + "\]";
	
	/* The following pattern applies if the "user" is a quoted string (in
	which case, there are no rules about which characters are allowed
	and which aren't; anything goes).  E.g. "jiminy cricket"@disney.com
	is a legal e-mail address. */
	
	var quotedUser="(\"[^\"]*\")";
	
	/* The following pattern applies for domains that are IP addresses,
	rather than symbolic names.  E.g. joe@[123.124.233.4] is a legal
	e-mail address. NOTE: The square brackets are required. */
	
	var ipDomainPat=/^\[(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})\]$/;
	
	/* The following string represents an atom (basically a series of non-special characters.) */
	
	var atom=validChars + '+';
	
	/* The following string represents one word in the typical username.
	For example, in john.doe@somewhere.com, john and doe are words.
	Basically, a word is either an atom or quoted string. */
	
	var word="(" + atom + "|" + quotedUser + ")";
	
	// The following pattern describes the structure of the user
	
	var userPat=new RegExp("^" + word + "(\\." + word + ")*$");
	
	/* The following pattern describes the structure of a normal symbolic
	domain, as opposed to ipDomainPat, shown above. */
	
	var domainPat=new RegExp("^" + atom + "(\\." + atom +")*$");
	
	/* Finally, let's start trying to figure out if the supplied address is valid. */
	
	/* Begin with the coarse pattern to simply break up user@domain into
	different pieces that are easy to analyze. */
	
	var matchArray=emailStr.match(emailPat);
	
	if (matchArray==null)
	{
	
		/* Too many/few @'s or something; basically, this address doesn't
		even fit the general mould of a valid e-mail address. */
	
		//alert("Email address seems incorrect (check @ and .'s)");
		return false;
	}
	var user=matchArray[1];
	var domain=matchArray[2];
	
	// Start by checking that only basic ASCII characters are in the strings (0-127).
	
	for (i=0; i<user.length; i++)
	{
		if (user.charCodeAt(i)>127)
		{
			//alert("Ths username contains invalid characters.");
			return false;
	    }
	}
	
	for (i=0; i<domain.length; i++)
	{
		if (domain.charCodeAt(i)>127)
		{
			//alert("Ths domain name contains invalid characters.");
			return false;
		}
	}
	
	// See if "user" is valid 
	
	if (user.match(userPat)==null)
	{
	
		// user is not valid
		
		//alert("The username doesn't seem to be valid.");
		return false;
	}
	
	/* if the e-mail address is at an IP address (as opposed to a symbolic
	host name) make sure the IP address is valid. */
	
	var IPArray=domain.match(ipDomainPat);
	if (IPArray!=null)
	{
	
	// this is an IP address
	
		for (var i=1;i<=4;i++)
		{
			if (IPArray[i]>255)
			{
				//alert("Destination IP address is invalid!");
				return false;
	   		}
		}
		return true;
	}
	
	// Domain is symbolic name.  Check if it's valid.
	 
	var atomPat=new RegExp("^" + atom + "$");
	var domArr=domain.split(".");
	var len=domArr.length;
	for (i=0;i<len;i++)

	{
		if (domArr[i].search(atomPat)==-1)
		{
			//alert("The domain name does not seem to be valid.");
			return false;
	    }
	}
	
	/* domain name seems valid, but now make sure that it ends in a
	known top-level domain (like com, edu, gov) or a two-letter word,
	representing country (uk, nl), and that there's a hostname preceding 
	the domain or country. */
	
	if (checkTLD && domArr[domArr.length-1].length!=2 && domArr[domArr.length-1].search(knownDomsPat)==-1)
	{
		//alert("The address must end in a well-known domain or two letter " + "country.");
		//alert("Dia chi email phai ket thuc bang cac ten mien da co nhu .com, .net, .org, .info,.. hoac hai ky tu .dat nuoc vi du .vn, .us,.." );
		return false;
	}
	
	
	// Make sure there's a host name preceding the domain.
	
	if (len<2)
	{
		//alert("This address is missing a hostname!");
		return false;
	}
	
	// If we've gotten this far, everything's valid!
	return true;
}

function checkloadjscssfile(filename, filetype)
{
	if (filesadded.indexOf("["+filename+"]")==-1)
	{
		loadjscssfile(filename, filetype)
		filesadded+="["+filename+"]"
	}
}

function loadjscssfile(filename, filetype)
{
	if (filetype=="js") //if filename is a external JavaScript file
	{ 
		var fileref=document.createElement('script')
		fileref.setAttribute("type","text/javascript")
		fileref.setAttribute("src", filename)
	}
	else if (filetype=="css") //if filename is an external CSS file
	{ 
		var fileref=document.createElement("link")
		fileref.setAttribute("rel", "stylesheet")
		//fileref.setAttribute("media", "screen, projection, print")
		fileref.setAttribute("type", "text/css")
		fileref.setAttribute("href", filename)
	}
	
	if (typeof fileref!="undefined")
	document.getElementsByTagName("head")[0].appendChild(fileref)
}

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.userAgent,
			subString: "OmniWeb",
			versionSearch: "OmniWeb/",
			identity: "OmniWeb"
		},
		{
			string: navigator.vendor,
			subString: "Apple",
			identity: "Safari"
		},
		{
			prop: window.opera,
			identity: "Opera"
		},
		{
			string: navigator.vendor,
			subString: "iCab",
			identity: "iCab"
		},
		{
			string: navigator.vendor,
			subString: "KDE",
			identity: "Konqueror"
		},
		{
			string: navigator.userAgent,
			subString: "Firefox",
			identity: "Firefox"
		},
		{
			string: navigator.vendor,
			subString: "Camino",
			identity: "Camino"
		},
		{		// for newer Netscapes (6+)
			string: navigator.userAgent,
			subString: "Netscape",
			identity: "Netscape"
		},
		{
			string: navigator.userAgent,
			subString: "MSIE",
			identity: "Explorer",
			versionSearch: "MSIE"
		},
		{
			string: navigator.userAgent,
			subString: "Gecko",
			identity: "Mozilla",
			versionSearch: "rv"
		},
		{ 		// for older Netscapes (4-)
			string: navigator.userAgent,
			subString: "Mozilla",
			identity: "Netscape",
			versionSearch: "Mozilla"
		}
	],
	dataOS : [
		{
			string: navigator.platform,
			subString: "Win",
			identity: "Windows"
		},
		{
			string: navigator.platform,
			subString: "Mac",
			identity: "Mac"
		},
		{
			string: navigator.platform,
			subString: "Linux",
			identity: "Linux"
		}
	]
};