This feature is obsolete. Although it may still work in some browsers, its use is discouraged since it could be removed at any time. Try to avoid using it.

This feature is non-standard and is not on a standards track. Do not use it on production sites facing the Web: it will not work for every user. There may also be large incompatibilities between implementations and the behavior may change in the future.

The onclose property of the WorkerGlobalScope interface represents an EventHandler to be called when the close event occurs and bubbles through the Worker.

This non-standard event handler was only implemented by a few browsers and has been removed from all or nearly all of them.


self.onclose = function() { ... };


The following code snippet shows an onclose handler set inside a worker:

self.onclose = function() {
  console.log('Your worker instance has been closed');


This feature is no longer defined in any specifications.

Browser compatibilityUpdate compatibility data on GitHub

Chrome Edge Firefox Internet Explorer Opera Safari
Basic support 4 ? 3.5 — 50 Yes 11.5 4
Android webview Chrome for Android Edge Mobile Firefox for Android Opera for Android iOS Safari Samsung Internet
Basic support ? 40 No 4 — 50 Yes 5.1 4.0

See also

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