Hello, is there any way to change the mask expression of the webinput on the client side?

Currently I'm trying to achieve it using the following web input

  <ISWebInput:WebInput ID="customInput" runat="server">

            <EditFormat IsEnabled="True" Type="Other">

                         <ErrorWindowStyle ForeColor="Red">

                           </ErrorWindowStyle>

                           <MaskInfo MaskExpression="000-00-0000"  SkipOptional="False">

                           </MaskInfo>

                           <ErrorWindowInfo IsEnabled="True">

                           </ErrorWindowInfo>

                       </EditFormat>

        </ISWebInput:WebInput>

Below is the code, which I implemented in javascript to change the masking

 var inputObj = ISGetObject("wiApiNum");

  inputObj.EditFormat.MaskInfo.MaskExpression = "aa-aaaa-aaaaa-aa-a-9";

But Unfortunately it does not work, is there any solution for my problem which can be implemented on the client side? If so could you please suggest me with a feasible solution.

Thanks,

Phanindra Kuncharapu.