BackgroundFetchRegistration: progress event

Limited availability

This feature is not Baseline because it does not work in some of the most widely-used browsers.

Experimental: This is an experimental technology
Check the Browser compatibility table carefully before using this in production.

Note: This feature is available in Web Workers.

The progress event of the BackgroundFetchRegistration interface thrown when the associated background fetch progresses.

Practically, this event is fired when any of the following properties will return a new value:


Use the event name in methods like addEventListener(), or set the onprogress event property on the relevant BackgroundFetchRegistration object.

addEventListener("progress", (event) => { })
onprogress = (event) => { }

Event type

A generic Event with no added properties.


The following example demonstrates how to log the progress of a download. The code first checks that a downloadTotal was provided when the background fetch was registered. This is then used to calculate the percentage, based on the downloaded property.

bgFetch.addEventListener("progress", () => {
  if (!bgFetch.downloadTotal) return;
  const percent = Math.round(
    (bgFetch.downloaded / bgFetch.downloadTotal) * 100,
  console.log(`Download progress: ${percent}%`);


Background Fetch
# background-fetch-registration-events

Browser compatibility

BCD tables only load in the browser