WindowEventHandlers.onunhandledrejection

The onunhandledrejection property of the WindowEventHandlers mixin is the EventHandler for processing unhandledrejection events. These events are raised for unhandled Promise rejections.

Syntax

window.onunhandledrejection = function;

Value

function is an EventHandler or function to call when unhandledrejection events are received by the window. The event handler receives as an input parameter as a PromiseRejectionEvent.

Examples

This example simply logs unhandled rejections' reason values to the console.

window.onunhandledrejection = function(e) {
  console.log(e.reason);
}

Specifications

Specification Status Comment
HTML Living Standard
The definition of 'onunhandledrejection' in that specification.
Living Standard Initial definition.

Browser compatibility

DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
onunhandledrejectionChrome Full support 49Edge Full support ≤79Firefox Full support 69
Full support 69
Full support 68
Disabled
Disabled From version 68: this feature is behind the dom.promise_rejection_events.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Partial support 55
Notes Disabled
Notes This event handler was added in Firefox 55 but was disabled since it wasn't fully implemented. It was fully implemented in Firefox 68 and enabled by default in Firefox 69.
Disabled From version 55: this feature is behind the dom.promise_rejection_events.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
IE No support NoOpera Full support 36Safari Full support 11WebView Android Full support 49Chrome Android Full support 49Firefox Android Full support 68
Disabled
Full support 68
Disabled
Disabled From version 68: this feature is behind the dom.promise_rejection_events.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Partial support 55
Notes Disabled
Notes This event handler was added in Firefox 55 but was disabled since it wasn't fully implemented. It was fully implemented in Firefox 68 but not enabled by default.
Disabled From version 55: this feature is behind the dom.promise_rejection_events.enabled preference (needs to be set to true). To change preferences in Firefox, visit about:config.
Opera Android No support NoSafari iOS Full support 11.3Samsung Internet Android Full support 5.0

Legend

Full support
Full support
No support
No support
See implementation notes.
See implementation notes.
User must explicitly enable this feature.
User must explicitly enable this feature.