Each section in Activity Stream displays data from a corresponding section feed in a standardised Section UI component. Each section feed is responsible for listening to events and updating the section options such as the title, icon, and rows (the cards for the section to display).

The Section UI component displays the rows provided by the section feed. If no rows are available it displays an empty state consisting of an icon and a message. Optionally, the section may have a info option menu that is displayed when users hover over the info icon.

On load, SectionsManager and SectionsFeed in SectionsManager.sys.mjs add the sections configured in the BUILT_IN_SECTIONS map to the state. These sections are initially disabled, so aren’t visible. The section’s feed may use the methods provided by the SectionsManager to enable its section and update its properties.

The section configuration in BUILT_IN_SECTIONS consists of a generator function keyed by the pref name for the section feed. The generator function takes an options argument as the only parameter, which is passed the object stored as serialised JSON in the pref {feed_pref_name}.options, or the empty object if this doesn’t exist. The generator returns a section configuration object which may have the following properties:






Non-optional unique id.


Localisation object

Has property id, the string localisation id, and optionally a values object to fill in placeholders.



Icon id. New icons should be added in icons.scss.



Maximum number of rows of cards to display. Should be >= 1.


Array of strings

The menu options to provide in the card context menus.



If true, will the section preference in the preferences pane will not be shown.



Configures the section preference to show in the preferences pane. Has properties titleString and descString.



Configures the empty state of the section. Has properties message and icon.

Section feeds

Each section feed should be controlled by the pref feeds.section.{section_id}.

Enabling the section

The section feed must listen for the events INIT (dispatched when Activity Stream is initialised) and FEED_INIT (dispatched when a feed is re-enabled having been turned off, with the feed id as the data). On these events it must call SectionsManager.enableSection(id). Care should be taken that this happens only once SectionsManager has also initialised; the feed can use the method SectionsManager.onceInitialized().

Disabling the section

The section feed must have an uninit method. This is called when the section feed is disabled by turning the section’s pref off. In uninit the feed must call SectionsManager.disableSection(id). This will remove the section’s UI component from every existing Activity Stream page.

Updating the section rows

The section feed can call SectionsManager.updateSection(id, options) to update section options. The rows array property of options stores the cards of sites to display. Each card object may have the following properties:

  type, // One of the types in Card/types.js, e.g. "Trending"
  title, // Title string
  description, // Description string
  image, // Image url
  url // Site url