Here's a proposed function:

function getOriginOfURL(url) {
    var domain = /https?:\/\/(www\.)?[-a-zA-Z0-9._]{2,256}(\.[a-z]{2,6})?(:[0-9]+)?\//i;
    return url.match(domain)[0];
}

@kaz231 There is a similar problem when one uses the /js directory as pkBaseURL, as described here: https://github.com/piwik/piwik/blob/2.16.0-b1/js/README.md. You would just need to call setAPIUrl() respectively in your tracker code on the tracked website. E.g. with the old synchronous tracker: After the piwikTracker definition:

var piwikTracker = Piwik.getTracker(pkBaseURL + "js/", 1);

add following line:

piwikTracker.setAPIUrl(pkBaseURL);

The closest one comes to in terms of documentation on this is following under https://piwik.org/docs/page-overlay/#page-overlay-troubleshooting:

Page Overlay tries to load scripts and data from the URL you pass to the Piwik tracker. If you have a restrictive mod_proxy setup or there’s another reason why this doesn’t work, use the method setAPIUrl(apiUrl) of the Piwik tracker to let it know from which URL it should load the scripts and the data. The parameter apiUrl has to point to the root directory of piwik, e.g. http://piwik.example.org/
or https://example.org/piwik/. The call to setAPIUrl has to be made before calling trackPageView.

See also: http://forum.piwik.org/t/piwik-1-10-page-overlay/8706?page=3

Please note that if using the /js directory as described in that README.md file, you won't need to do the "Deployment" part. It's already done. You would just need to:

change your tracking code to use "js/" instead of "piwik.js" and "piwik.php", respectively

@piwik-devs On a side note, the above information could be added to the above README.md file. Alternatively, the call of setAPIUrl(pkBaseURL) could be part of the generated tracker code by default.

@piwik-devs On a side note, the above information could be added to the above README.md file.

PR: #9470

Unfortunately, this won't work as we can't update quickly tracking codes on hundreds of websites.

Maybe it would be easier and more fail proof to check whether it ends with .php and if so, remove everything after the last / slash.

In such case https://github.com/piwik/piwik/blob/master/js/tracker.php won't work.

We could on top check for an ending /js/ after removing the filename. I just want to avoid complicated regex like mentioned above that probably don't work in all cases (eg URLs can contain various characters etc.) . I'd keep it as simple as possible and if it doesn't work for someone they still can use as mentioned by @Joey3000 the method setAPIUrl was specifically built for this use case. From the description: Set the URL of the Piwik API. It is used for Page Overlay. This method should only be called when the API URL differs from the tracker URL.

As I said, this is only to catch protocol://domain.tld[port]/ of given URL. We don't analyze rest of it, so that's why I didn't consider any other characters that could be available only in query path. This regex is really simple.

We goal is to have only domain with protocol and port at the end, because we found a case when Piwik tries to load resource from plugin, so removing of the filename won't give us anything. We want to fix it once and never come back to it. The solution that I proposed solves the problem.

What if Piwik is installed under sub.example.com/piwik/foo?

also: what if Piwik is installed under a unicode domain name? eg. http://ヒキワリ.ナットウ.ニホン

@mattab I thought about it and it's possible to handle it with regex in JS.
@tsteur good point ! Looks like indeed removing of the suffix is the only solution, which will work in all cases.
Thanks for the feedback !

Can you test this patch: #9775 ? I reckon it should fix it

Sure, I will test it this week.

@tsteur I tested and it works correctly.