how to get master page control Id from child page using javascript

[M Kumar]

hi sir,

I use the below code in server side to get the control id in child page while radcombox  control in master page.

  Dim radcmbx As RadComboBox = CType(Page.Master.FindControl("Database_List"), RadComboBox)

So how i get master page control id from separate JavaScript file using javascript or jquery,