How can i observe a specified Firefox event in a Firefox-Extension?

I want to wait for Firefox-Browser-Events (sessionstore-windows-restored, user-interaction-inactive,..) in order to clear the history. My Extension is able to clear the history on shortcut for now, but i don't know how to listen for such events. I already had a lood at observer notification, but nothing i tried se开发者_Go百科ems to work.

My extension code so far is here:

   (function() {

    (window.myObj =
    {
        myObserver : function()
        {
          this.register();
        },

        init : function()
        {
            try {

                myObserver.prototype = {
                    observe: function(subject, topic, data){

                        switch (topic) {
                          case 'sessionstore-windows-restored':
                            Firebug.Console.log('sessionstore-windows-restored observed');
                            myObj.clearHistory();
                            break;
                          case 'user-interaction-inactive':
                            Firebug.Console.log('user-interaction-inactive');
                            break;
                          case 'user-interaction-active':
                            Firebug.Console.log('user-interaction-active');
                            break;
                        }

                        Firebug.Console.log('HUI :' + subject + ','+topic+','+data);
                    },
                    register: function(){
                        var observerService = Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
                        observerService.addObserver(this, "readyToClearHistory", false);
                    },
                    unregister: function(){
                        var observerService = Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
                        observerService.removeObserver(this, "readyToClearHistory");
                    }
                }
            }
            catch (e) {
                Firebug.Console.log('MIST :' + e);
            }

            observer = new myObserver();
         },
         clearHistory : function(){
            var globalHistory = Components.classes["@mozilla.org/browser/global-history;2"].getService(Components.interfaces.nsIBrowserHistory);
            var now = Date.now();

            // clear one hour
            globalHistory.removeVisitsByTimeframe(now - 3600, now);

            try {
                var os = Components.classes["@mozilla.org/observer-service;1"].getService(Components.interfaces.nsIObserverService);
                os.notifyObservers(null, "browser:purge-session-history", "");
            } 
            catch (e) {

                // Clear last URL of the Open Web Location dialog
                var prefs = Components.classes["@mozilla.org/preferences-service;1"].getService(Components.interfaces.nsIPrefBranch2);
                try {
                    prefs.clearUserPref("general.open_location.last_url");
                } 
                catch (e) {
                }
            }
              } 
  }
}

Some example code would be nice. What do i need to solve this issue?

---

I don't see anything wrong with with the parts of your code that are specific to nsIObserver, which means your problem is likely somewhere else. This complete example works:

var ObserverTest = {

    register: function() {
        var observerService = Components.classes["@mozilla.org/observer-service;1"]
            .getService(Components.interfaces.nsIObserverService);
        observerService.addObserver(ObserverTest, "user-interaction-active", false);
    },

    observe: function(subject, topic, data) {
        switch (topic) {
            case 'sessionstore-windows-restored':
                // do stuff
                break;
            case 'user-interaction-inactive':
                // do stuff
                break;
            case 'user-interaction-active':
                // every 5 seconds and immediately when user becomes active
                alert("active"); 
                break;
        }
    },

    unregister: function() {
        var observerService = Components.classes["@mozilla.org/observer-service;1"]
            .getService(Components.interfaces.nsIObserverService);
        observerService.removeObserver(ObserverTest, "user-interaction-active");
    }
}

window.addEventListener("load", ObserverTest.register, false);
window.addEventListener("unload", ObserverTest.unregister, false);

In general, I find it helpful to start with something very simple the first time I attempt to use an unfamiliar component, like what I've done above, so that I can isolate it from application-specific code and verify that I'm using it correctly. I don't pull it into the larger application until I know it's working.