ContentIndex.add()

The add() method of the ContentIndex interface registers an item with the content index.

ContentDescription

An Object containing the following data:

• id: A unique String identifier.
• title: A String title for the item. Used in user-visible lists of content.
• title: A String title of the item. Used in user-visible lists of content.
• description: A String description of the item. Used in user-visible lists of content.
• url: A String containing the url of the corresponding HTML document. Needs to be under the scope of the current service worker.
• category: Optional A String defining the category of content. Can be:
  • '' An empty String, this is the default.
  • homepage
  • article
  • video
  • audio
• icons: Optional An Array of image resources, defined as an Object with the following data:
  • src: A url String of the source image.
  • sizes: Optional A String representation of the image size.
  • type: Optional The MIME type of the image.

Returns a Promise that resolves with undefined

TypeError

This exception is thrown in the following conditions:

• The service worker's registration is not present or the service worker does not contain a FetchEvent.
• The id, title, description or url are missing, not of type String, or an empty String.
• The items referenced by icons are not of image type.

Here we're declaring an item in the correct format and creating an asynchronous function which uses the add method to register it with the content index.

// our content
const item = {
  id: 'post-1',
  url: '/posts/amet.html',
  title: 'Amet consectetur adipisicing',
  description: 'Repellat et quia iste possimus ducimus aliquid a aut eaque nostrum.',
  icons: [{
    src: '/media/dark.png',
    sizes: '128x128',
    type: 'image/png',
  }],
  category: 'article'
};

// our asynchronous function to add indexed content
async function registerContent(data) {
  const registration = await navigator.serviceWorker.ready;

  // feature detect Content Index
	if (!registration.index) {
		return;
	}

  // register content
  try {
		await registration.index.add(data);
  } catch (e) {
    console.log('Failed to register content: ', e.message);
  }
}

The add method can also be used within the service worker scope.

// our content
const item = {
  id: 'post-1',
  url: '/posts/amet.html',
  title: 'Amet consectetur adipisicing',
  description: 'Repellat et quia iste possimus ducimus aliquid a aut eaque nostrum.',
  icons: [{
    src: '/media/dark.png',
    sizes: '128x128',
    type: 'image/png',
  }],
  category: 'article'
};

self.registration.index.add(item);

• An introductory article on the Content Index API
• An app which uses the Content Index API to list and remove 'save for later' content
• Service Worker API, along with information about Cache and CacheStorage