var defaultEmptyOK = false;
var whitespace = " \t\n\r";
function isWhitespace (s)

{   var i;
    if (isEmpty(s)) return true;
    for (i = 0; i < s.length; i++)
    {   
        var c = s.charAt(i);

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

    return true;
}
function isEmpty(s){return ((s == null) || (s.length == 0))}
function isEmail(s)
{   if (isEmpty(s)) 
       if (isEmail.arguments.length == 1) return defaultEmptyOK;
       else return (isEmail.arguments[1] == true);
   
    if (isWhitespace(s)) return false;
	if (s.indexOf(' ') != "-1") return false;
    var i = 1;
    var sLength = s.length;

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

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

    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;
}