var whitespace = " \t\n\r";
function isEmpty(s) {
	return ((s == null) || (s.length == 0));
}
// Returns true if string s is empty or
// whitespace characters only.
function isWhitespace (s) {

		var i;

		// Is s empty?
		if (isEmpty(s)) return true;

		// Search through string's characters one by one
		// until we find a non-whitespace character.
		// When we do, return false; if we don't, return true.
		for (i = 0; i < s.length; i++)
		{
				// Check that current character isn't whitespace.
				var c = s.charAt(i);

				if (whitespace.indexOf(c) == -1) return false;
		}

		// All characters are whitespace.
		return true;
}
function isEmail (s) {

		// is s whitespace?
		if (isWhitespace(s)) return false;

		// there must be >= 1 character before @, so we
		// start looking at character position 1
		// (i.e. second character)
		var i = 1;
		var sLength = s.length;

		// look for @
		while ((i < sLength) && (s.charAt(i) != "@"))
		{ i++
		}

		if ((i >= sLength) || (s.charAt(i) != "@")) return false;
		else i += 2;

		// look for .
		while ((i < sLength) && (s.charAt(i) != "."))
		{ i++
		}

		// there must be at least one character after the .
		if ((i >= sLength - 1) || (s.charAt(i) != ".")) return false;
		else return true;
}