Useful and logically legitimate use of afore mentioned global variable hack. window.childWindow = window.open("thechild.html"); window.childWindow. document.write("i am the child window"); window.childWindow. window.document.title = "satanic spawn"; unfortunately you can't give the child window an attribute that can be read by that child, but you've always got window.opener, so control can go both ways. My previous problem was not solved by this, you still have to go window.open("","popup"); window.close("popup"); in order to close a popup window when you don't know if it exists.