How can I add, remove, or swap jQuery validation rules from a page?

Question

Note:
This question refers to a very old version of jQuery.validate() (version 1.5). This plugin now provides a built-in solution for doing this: the .r

Answer 1

$('#form_id').validate();//empty rules
//add rules/message to form element
$('#form_id #inputId').rules("add", {
    required        : true,                             
    messages        : {
        required    : 'Add your required message'
    }
});