Call javascript function from code behind in C#

Code in .asp page(java-script function)

  <script type="text/javascript">

        function showmodal_welcome() {

            window.parent.showmodal();
        }

        function hidePopup() {

            parent.$find('EditModalPopup').hide();
        }

     
    </script>

Code in .CS Page

Page page = HttpContext.Current.CurrentHandler as Page;
 ScriptManager.RegisterClientScriptBlock(page, page.GetType(), "", "showmodal_welcome();", true);