I have scenario like P is parent page and from that page one child page is being open using window.open(C) where C is child page. Now I have to navigate in same child window. Let's call that page as C1. 

I found when I try to access one button of page P from page C1, it gave me not found.
My syntaxt is like (in page C1),

```
window.opener.document.getElementById('xyz');

```

Is there any way using which I can identify the page I am getting in window.opener is same page what I am looking for?