SmartClient ComboBoxItem limiting number of characters

Hello,

I have a requirement in smart client where i need to type minimum 3 characters before hitting the rest call to the server.I am using ComboBoxItem , the version i am using for smart client is 8.3

My events is getting fired on keyup event. I tired with creating dummy DS and using dataProtocol: "clientCustom".
I also have tired with overriding keyup event.

I am implementing this change on client side(javascript). Could you please help me with the approach for troubleshooting this?

How can I prevent server call before certain number of characters?

Thanks,