This feature is obsolete.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 event handler has been removed from the specifications below.

Specification Status Comment
WHATWG HTML Living Standard
The definition of 'WorkerGlobalScope.onclose' in that specification.
Living Standard No change from Web Workers.
Web Workers
The definition of 'WorkerGlobalScope.onclose' in that specification.
Editor's Draft Initial definition.

Browser compatibility

Feature Chrome Firefox (Gecko) Microsoft Edge Internet Explorer Opera Safari
Basic support 4 3.5 (1.9.1) through 50 (50) ? (Yes) 11.5 4
Feature Android Chrome for Android Firefox Mobile (Gecko) Firefox OS (Gecko) IE Mobile Opera Mobile Safari Mobile
Basic support ? 40 1.0 (1.9.1) through 50.0 (50) 1.0.1 (Yes) (Yes) 5.1

See also

Document Tags and Contributors

 Contributors to this page: Sheppy, teoli, chrisdavidmills, kscarfone
 Last updated by: Sheppy,