Question

I have two password fields

pwd1 and pwd2

I am using jquery plugin http://bassistance.de/jquery-plugins/jquery-plugin-validation/

How to make pwd1 and pwd2 to be required and equal if and only if any one of the field is non-empty ?

Answer 1

You can use an equalTo rule, as @voigtan suggests, but store the required rule in the element’s class. That will allow you to enable or disable the rule at will:

var $passwords = $("input:password");
$passwords.change(function() {
    if ($passwords.filter(function() {
        return $.trim($(this).val()).length > 0;
    }).length > 0) {
        $passwords.addClass("required");
    } else {
        $passwords.removeClass("required");
    }
});
$("form").validate({
    rules: {
        "confirm-password": {
            equalTo: "#password"
        }
    }
});

You can test it in this fiddle.