Monitor window opening, closing, DOMContentLoaded events for all current & future windows+tabs

Question

Background:

I'm authorised to "automate" a 3rd party site for the purpose of pushing "service orders" into it and monitoring the progress of those requests.

I tried taking a normal "scraping" approach (using WWW::Mechanize, HTML::Query, etc from Perl) but ran into a lot of issues predicting what the JavaScript in the site would do under a variety of circumstances. I intend to go back to this approach if I ever receive support from the vendor of the product which runs the 3rd party site, or can get hold of some better documentation w.r.t business-rules of the product.

To avoid second guessing the JavaScript code, and to save a lot of time, I ended up taking an approach were I load the 3rd party site in Firefox on a dedicated VM, and then execute "privileged" code (i.e: nsI*) in the context of the site to "drive" and "scrape" the site.

I'm currently using nsIWebProgressListener/DOMContentLoaded (when I already have a reference to a ChromeWindow), and nsIWindowMediator window+tab enumeration called from setInterval to find new windows and tabs (when I have no way to predict them opening, nor gain a reference to their DOMWindow objects due to scoping of 3rd party JavaScript).

Question: How can I automatically install a "hook" into each Window/Tab opened now (and in the future) by the 3rd party site's JavaScript? Something like a "window watcher" nsI~ interface for the whole of the Firefox UI would be very useful in this case.

Answer 1

There are so many ways you could do this, so the right choice depends on how you're going about everything else.

Here are just a few ways of listening, rather than polling.

1. New Chrome Windows

   function ChromeWindowObserver() {
       this.observe = function(subject, topic, data) {
          // subject is a ChromeWindow
       }
   }
   Components.classes["@mozilla.org/embedcomp/window-watcher;1"]
         .getService(Components.interfaces.nsIWindowWatcher)
         .registerNotification(new ChromeWindowObserver());
   

2. New Tabs

   function tabListener(event) {
       var browser = gBrowser.getBrowserForTab(event.target):
   }
   gBrowser.tabContainer.addEventListener("TabOpen", tabListener, false);
   

3. Observer Notifications (my favorite)

   const dumpObserver = {
       observe: function(subject, topic, data) { dump(topic + "\n"); }
   }
   const domObserver = {
       observe: function(subject, topic, data) { dump(subject.location + "\n"); }
   }
   const ObserverService = Components.classes["@mozilla.org/observer-service;1"]
         .getService(Components.interfaces.nsIObserverService);
   
   /* debug log notifications */
   ObserverService.addObserver(dumpObserver, "*", false);
   /* debug log all new content locations */
   ObserverService.addObserver(domObserver, "content-document-global-created", false);
   

Side note, check out JavaScript code modules. I think that might be helpful for you when sharing data between chrome windows.