In Internet Explorer, when you call the method window.open in javascript it does not pass the referring url to the new window that is created. This happens because the request to the page in the new window does not contain the HTTP Referer header. Therefore if you try to access the document.referrer variable in javascript or the $_SERVER['HTTP_REFERER'] variable in PHP from the new window they both will not be set. In FireFox it works fine, and the referring url is passed to the new window in the HTTP headers. But since most of the people in the world use Internet Explorer a workaround must be put in place.

Instead of doing the following

<a href="javascript:window.open('newurl.php','','');">
click here</a>

We can pretty much simulate the same effect with a simple target=”_blank”

<a href="newurl.php" target="_blank">click here</a>

Furthermore, if you are only planning on accessing the referring url in javascript and not in PHP you can access the window.opener object and you can still mantain the use of window.open.

var ReferringUrl = "";

if (document.referrer)
  ReferringUrl = document.referrer.toString();
if (window.opener && window.opener.location)
  ReferringUrl = window.opener.location.toString();

That script will allow you to retrieve the referring url in the new window through javascript but it will still be unaccessible through PHP.

So to allow tracking of the referring url using window.open so that it is available in javascript and PHP we can implement the following, where we actually send the referring url and other such data to through the url in the query string.

<a href="javascript:window.open('newurl.php?' + urlencode
(document.location.toString()),'','height=200,width=150');">
click here</a>

That script will allow you to maintain the use of window.open and still be able to get the referring url in both javascript through the parsing of document.location in the new popup window and through PHP using the $_REQUEST['referringurl'] variable. Note that urlencode is not a native javascript function.

This entry was posted on Thursday, July 27th, 2006 at 3:50 pm and is filed under Programming. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.