The updateUI() method of the BackgroundFetchUpdateUIEvent interface updates the title and icon in the user interface to show the status of a background fetch.

This method may only be run once, to notify the user on a failed or a successful fetch.

options Optional

An object containing any of the following:

icons Optional

A list of one or more image resources, containing icons for use in the user interface. An image resource is an object containing:

src

A string which is a URL of an image.

sizes Optional

A string which is equivalent to a <link> sizes attribute.

type Optional

A string containing an image MIME type.

label Optional

A string providing a name for the associated image.

title Optional

A string containing the new title of the user interface.

A Promise.

InvalidStateError DOMException

Returned if any of the following are true:

• The isTrusted property is false.
• The BackgroundFetchUpdateUIEvent UI updated flag is already set, indicating that the updateUI() method has already been called.
• The BackgroundFetchUpdateUIEvent is not active.

The following example demonstrates updating the UI with a title and image icon on a successful fetch.

addEventListener("backgroundfetchsuccess", (event) => {
  event.updateUI({
    title: "Episode 5 ready to listen!",
    icon: {
      src: "path/to/success.ico",
      sizes: "16x16 32x32 64x64",
    },
  });
});