Disabling/enabling requiredFieldValidators with javascript and server side

Question

I have a drop down (dropdown2) that is required IF there is something in it but it\'s options data is driven by ajax from another dropdown (dropdown1) selec

Answer 1

DISABLE

document.getElementById("<%=ReqVal.ClientID%>").style.visibility = "hidden"; 

document.getElementById("<%=ReqVal.ClientID%>").enabled = false;

ENABLE

document.getElementById("<%=ReqVal.ClientID%>").style.visibility = "visible"; 

document.getElementById("<%=ReqVal.ClientID%>").enabled = true;