Coldfusion with jquery

I have facing one proble in jquery and coldfusion.

I have one select box on toggleing of tht select i populated some feils and hide  some another feid.The problem is tht whn i submit it asking to fill tht hidden feilds.I tried to change the required attrbute of tht feilds to false and true for new visbile feilds in jquery but not succedded in my way..i can change other attribute like disable and all but "required " is not getting..

any one please help?

<cftextarea name="comments"

                                                id="rationale"

                                                rows="5"

                                                cols="60"

                                                message="Please enter a response for comments">

                                                #comments#

                                    </cftextarea>

<script type="text/javascript">

jQuery(document).ready(function(){

            $("#comments").rules("add", {

             required: true,

            minlength: 2,

            messages: {

             required: "Required input",

             minlength: jQuery.format("Please, at least {0} characters are necessary")

            }

            });

});

</script>

Any workaround for this?