var whitespace = " \t\n\r";

function isEmpty(s)
{   
    var i;

    if ((s == null) || (s.length == 0)) return true;

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

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

    return true;
    
    return ((s == null) || (s.length == 0))
}

function isEmail(s)
{   
    if (isEmpty(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;
}

function isZipcode(strZip)
{
	var s = new String(strZip);

	if (s.length != 5 && s.length != 10)
		return false;

	for (var i=0; i < s.length; i++)
		if ((s.charAt(i) < '0' || s.charAt(s) > '9') && s.charAt(i) != '-')
			return false;

	return true;
}