Control firefox tabs

Question

(per your comment....)

To create an addon that logs TAB 'load' events, create a bootstrapped (restartless) addon:

bootstrap.js (The JavaScript file containing your 'privileged' code)
install.rdf (an XML file describing your addon to Firefrox)

To build the addon, simply place both files inside the top-level (no folders!) of a ZIP file with the file extension .xpi. To install the addon, navigate to about:addons then from the tools menu, click Install from file, find your XPI, open it, then after a short delay choose Install.

In install.rdf put something like this:

<?xml version="1.0"?>
<RDF xmlns="http://www.w3.org/1999/02/22-rdf-syntax-ns#" 
     xmlns:em="http://www.mozilla.org/2004/em-rdf#">
    <Description about="urn:mozilla:install-manifest">
        <em:id>youraddonname@yourdomain</em:id>
        <em:type>2</em:type>
        <em:name>Name of your addon</em:name>
        <em:version>1.0</em:version>
        <em:bootstrap>true</em:bootstrap>
        <em:description>Describe your addon.</em:description>
        <em:creator>Your name</em:creator>

        <!-- Firefox Desktop -->
        <em:targetApplication>
            <Description>
                <em:id>{ec8030f7-c20a-464f-9b0e-13a3a9e97384}</em:id>
                <em:minVersion>4.0.*</em:minVersion>
                <em:maxVersion>29.0.*</em:maxVersion>
            </Description>
        </em:targetApplication>
    </Description>
</RDF>

You need to implement two mandatory JavaScript functions in the bootstrap.js:

startup() - called when you install the addon, and when your browser starts up.
shutdown() - called when you uninstall the addon, and when your browser shuts down.

You should call all of the 'privileged' code from startup(). For hygiene, you can (and probably should) also implement install() and uninstall() functions.

Start by implementing the following code in bootstrap.js:

const Cc = Components.classes;
const Ci = Components.interfaces;
let consoleService = Cc["@mozilla.org/consoleservice;1"]
                        .getService(Ci.nsIConsoleService);
let wm             = Cc["@mozilla.org/appshell/window-mediator;1"]
                        .getService(Ci.nsIWindowMediator);

function LOG(msg) {
  consoleService.logStringMessage("EXTENSION: "+msg);    
}

function startup() {
  try {
    LOG("starting up...");
    let windows = wm.getEnumerator("navigator:browser");
    while (windows.hasMoreElements()) {
      let chromeWindow = windows.getNext().QueryInterface(Ci.nsIDOMWindow);
      WindowListener.setupBrowserUI(chromeWindow);
    }
    wm.addListener(WindowListener);
    LOG("done startup.");
  } catch (e) {
    LOG("error starting up: "+e);
  }
}

function shutdown() {
  try {
    LOG("shutting down...");
    let windows = wm.getEnumerator("navigator:browser");
    while (windows.hasMoreElements()) {
      let chromeWindow = windows.getNext().QueryInterface(Ci.nsIDOMWindow);
      WindowListener.tearDownBrowserUI(chromeWindow);
    }
    wm.addListener(WindowListener);
    LOG("done shutdown.");
  } catch (e) {
    LOG("error shutting down: "+e);
  }
}

Basically, that calls WindowListener.setupBrowserUI() for each current & future window of your web-browser. WindowListener is defined as follows:

var WindowListener = {
  setupBrowserUI: function(chromeWindow) {
    chromeWindow.gBrowser.addEventListener('load', my_load_handler, true);
  },
  tearDownBrowserUI: function(chromeWindow) {
    chromeWindow.gBrowser.removeEventListener('load', my_load_handler, true);
  },
  onOpenWindow: function(xulWindow) {
    let chromeWindow = xulWindow.QueryInterface(Ci.nsIInterfaceRequestor)
                         .getInterface(Ci.nsIDOMWindow);
    chromeWindow.addEventListener("load", function listener() {
      chromeWindow.removeEventListener("load", listener, false);
      var domDocument = chromeWindow.document.documentElement;
      var windowType = domDocument.getAttribute("windowtype");
      if (windowType == "navigator:browser")
        WindowListener.setupBrowserUI(chromeWindow);
    }, false);
  },
  onCloseWindow: function(chromeWindow) { },
  onWindowTitleChange: function(chromeWindow, newTitle) { }
};

That sets up an event listener for the OpenWindow event, and in turn installs an event listener for load events in the TabBrowser of each ChromeWindow. The load event handler is defined as:

var my_load_handler = function (evt) {
  try {
    var browserEnumerator = wm.getEnumerator("navigator:browser");
    while (browserEnumerator.hasMoreElements()) {
      var browserWin = browserEnumerator.getNext();
      var tabbrowser = browserWin.gBrowser;
      var numTabs = tabbrowser.browsers.length;
      for (var index = 0; index < numTabs; index++) {
        var currentBrowser = tabbrowser.getBrowserAtIndex(index);
        var domWindow = currentBrowser.contentWindow.wrappedJSObject;
        if (!domWindow.hasOwnProperty('__logged_this_window__')) {
          LOG("TAB loaded:");
          LOG("   URL: "+domWindow.location.href);
          LOG("   TITLE: "+domWindow.title)
          domWindow.__logged_this_window__ = 1;
        }
      }
    }
  } catch (e) {
    LOG(e);
  }
}

So basically, if there's a load event on any of the TabBrowser elements in Firefox, that function will run. It'll enumerate all of the Firefox windows, and all of those windows' tabs (Browser elements). The trick is that when a page reloads all the custom properties on a "content" DomWindow are lost, so we check to see if a custom property is present. If not, then we log details of the TAB's content page.