// whitespace characters
    var whitespace = " \t\n\r";
    
    // Check whether string s is empty.
    function isEmpty(s) { 
        return ((s == null) || (s.length == 0)) 
    }
    
    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 isValidEmail(str) {
        return (str.indexOf(".") > 3) && (str.indexOf("@") > 0) && (str.indexOf(".") > (str.indexOf("@")+1)) && (str.indexOf(".") < (str.length-1));
    }