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:
uploaded,downloaded,result, orfailureReason.
Syntax
Use the event name in methods like addEventListener(), or set an event handler property.
addEventListener("progress", (event) => { })
onprogress = (event) => { }
Event type
A generic Event with no added properties.
Example
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}%`);
});
Specifications
| Specification |
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| Background Fetch # background-fetch-registration-events |
Browser compatibility
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progress event
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Legend
Tip: you can click/tap on a cell for more information.
- Full support
- Full support
- No support
- No support
- Experimental. Expect behavior to change in the future.