Okay, so despite the fact that I'm following the Telerik example here
to the letter...
var combo = <%= RadComboBox1.ClientID %>;
[For what it's worth, document.getElementById('<%= RadComboBox1.ClientID %>') evaluates to object HTMLDivElement.]
I just want to be able to grab hold of my ComboBox from the client side, and I'm baffled why the seemingly-basic example on the Telerik website is failing for me. Thanks for your help.