gistfile1.js

// PREFS.JS

/**
 * Retrieve the value of the homepage preference
 *
 * @memberOf prefs
 * @param {Boolean|Number|String|Object} [aDefaultValue]
 *        Default value which will be used if the preference doesn't exist.
 * @param {PrefBranch} [aBranch]
 *        Preferences branch to use.
 *
 * @returns {Boolean|Number|String|Object} The value of the preference
 */
function getHomepagePref(aDefaultValue, aBranch) {
  return getPref(Ci.nsIPrefLocalizedString, "browser.startup.homepage",
                 aDefaultValue, aBranch);
}


// TEST.JS

var prefs = require("../../../lib/prefs");
...
prefs.getHomepagePref(undefined, prefs.defaultBranch)