User-friendly uninstall process of an extensions

As a rule you need to perform few steps when user uninstalls your extension.

1. Remove all data that was added by your extension.
2. Open feedback page.

Below you will find some code that performs all these actions:


const MY_EXT_PREF_BRANCH = "extensions.my_ext";
const Cc = Components.classes; 
const Ci = Components.interfaces; 

var my_ext = {
  preferencesService : Cc["@mozilla.org/preferences-service;1"].
          getService(Ci.nsIPrefBranch),
    
  observerService : Cc['@mozilla.org/observer-service;1'].
          getService(Ci.nsIObserverService),

  PLUGIN_UUID : "{a704f080-166f-12de-8c30-0206200c9a66}",

  PAGE_FEEDBACK : "http://mysite.com/feedback",

  uninstallObserver : {
    observe: function(aSubject, aTopic, aData)
    {
       try {
          var item = aSubject.QueryInterface(Ci.nsIUpdateItem);

          if (item.id != my_ext.PLUGIN_UUID) {
            return;
          }

          if (aData == "item-uninstalled") {
            gBrowser.selectedTab = gBrowser.addTab(my_ext.PAGE_FEEDBACK);

            // Remove all properties that was installed by our extension
            my_ext.preferencesService.deleteBranch(MY_EXT_PREF_BRANCH);
          }
        } catch (e) {
      }
    }
  },

  addUninstallObserver : function() {
    my_ext.observerService.addObserver(my_ext.uninstallObserver, "em-action-requested", false);
  }
};

my_ext.addUninstallObserver();