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) => { }
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}%`);
});