Assuming you are calling your function at some point, the following different techniques will work:
Although, I only tested in Firefox. By the way, I wasn't sure about this approach so I spent 5 minutes googling and found the answer for you. The internet is littered with thousands of sites showing how to access frames and documents and forms. Where did you look?
I'm just a poor boy, I need no sympathy, because I'm easy come, easy go, little high, little low, little ad