gistfile1.js

/* global SettingsListener */

'use strict';

navigator.mozL10n.once(function fmd_menu_l10n_ready() {
  SettingsListener.observe('findmydevice.enabled', false,
    function fmd_menu_enabled_status(value) {
      var _ = navigator.mozL10n.get;
      var desc = document.getElementById('findmydevice-desc');
      desc.textContent = value ? _('enabled') : _('disabled');
    });
});

// maybe this instead?

/* global SettingsListener */

'use strict';

navigator.mozL10n.once(function loadWhenIdle() {
  var idleObserver = {
    time: 4,
    onidle: function fmd_menu_l10n_ready() {
      SettingsListener.observe('findmydevice.enabled', false,
        function fmd_menu_enabled_status(value) {
          var _ = navigator.mozL10n.get;
          var desc = document.getElementById('findmydevice-desc');
          desc.textContent = value ? _('enabled') : _('disabled');
        });
    }
  };
  navigator.addIdleObserver(idleObserver);
});