You probably misunderstood the property
window.opener
. If the content you show is placed in some HTML page, and you open this page with a browser using some URI (file name of HTTP/HTTPs URL, does not matter), it is apparent that the opener is null. There is no an "opener", which could be some "other window" which opened your browser window.
To understand it, please see:
http://www.w3schools.com/jsref/prop_win_opener.asp[
^].
—SA