Preferences Library, for Firefox older than its version 57.

This project is obsolete and not maintained anymore.

Usage

Developer-friendly utility (for bootstrapped extensions):

// you can create a new "store" which is bound to specific base key (domain).
var store = window['piro.sakura.ne.jp'].prefs.createStore('extensions.someextension');

// you can define new preference under the base key.
store.define('enabled' /* property name and key */,
             true      /* default value */);
// then it will be defined as: extensions.someextension.enabled=true
// and you can read the value as a static property like:
var enabled = store.enabled;
// the value will be updated automatically when the user change the preference.

// if you want to define the preference with a key different to the property name...
store.define('leftMargin', true, 'margin.left' /* the actual key */);

// after all, free the memory.
store.destroy();

Low level APIs (for legacy type addons):

var value = window['piro.sakura.ne.jp'].prefs.getPref('my.extension.pref');
window['piro.sakura.ne.jp'].prefs.setPref('my.extension.pref', true);
window['piro.sakura.ne.jp'].prefs.clearPref('my.extension.pref');

var listener = {
      domains : [
        'browser.tabs',
        'extensions.someextension'
      ],
      observe : function(aSubject, aTopic, aData)
      {
        if (aTopic != 'nsPref:changed') return;
        var value = window['piro.sakura.ne.jp'].prefs.getPref(aData);
      }
    };
window['piro.sakura.ne.jp'].prefs.addPrefListener(listener);
window['piro.sakura.ne.jp'].prefs.removePrefListener(listener);