javascript - document.getElementById disabled in ASP.NET site -

i found nice site build in asp.net. want try things on it, entering text input field through console, javascript, looks disabled. when try do:

document.getelementbyid("name"); 

i null, on each element try it. in js files of site see using getelementbyid in code, somehow it's disabled me.

you need use clientid. example here server control

<asp:textbox id="txtname" runat="server/> 

and want access javascript need following.

document.getelementbyid("<%=txtname.clientid%>").value;