RequiredFieldValidator still validates when hidden

Question

I have 2 fields that I need to validate, if they are displayed on the screen. When the Form initially loads, they are hidden and they will stay hidden unless an item is selected from a DropDown box. Once the value is selected, the 2 fields appear and then the validation is working correctly. However, if another value is selected that doesn't make these 2 fields appear, they are still being validated and not allowing the page to submit. Any ideas on how I can achieve this?

function DisplayOutageDates() {
    if ($('#ddImpact').val() == "Service Affecting") { 
    $('#outageDates').css('display',''); 
    document.getElementById('txtOutageStartDate').Visible = true;
    document.getElementById('RFVOutageStartDate').Visible = true;
    } else {
    $('#outageDates').css('display','none');
    document.getElementById('txtOutageStartDate').Visible = false;
    document.getElementById('RFVOutageStartDate').Visible = false;
    }
}

<asp:RequiredFieldValidator ID="RFVOutageStartDate" runat="server" 
    ControlToValidate="txtOutageStartDate" SetFocusOnError="true"
    ErrorMessage="Please enter the Outage Start Date" />

Answer 1

You can use :

ValidatorEnable(val, enable): 
Takes a client-validator and a Boolean value. 
Enables or disables a client validator. 
Being disabled will stop it from evaluating and it will always appear valid. 

Found on msdn.

Using Javascript this would look like:

ValidatorEnable(document.getElementById('<%=Validator1.ClientID%>'), state);
//where state would be a boolean 

In JQuery this would look like:

 ValidatorEnable($("#<%= Validator1.ClientID %>")[0], state);

As found here: http://codeclimber.net.nz/archive/2008/05/14/how-to-manage-asp.net-validation-from-javascript-with-jquery.aspx