PromiseRejectionEvent

The PromiseRejectionEvent interface represents events which are sent to the global script context when JavaScript Promises are rejected. These events are particularly useful for telemetry and debugging purposes.

For details on promise rejection events, see Promise rejection events in Using Promises.

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Constructor

PromiseRejectionEvent(): Creates a PromiseRejectionEvent event, given the type of event (unhandledrejection or rejectionhandled) and other details.

Properties

Also inherits properties from its parent Event.

PromiseRejectionEvent.promise Read only: The JavaScript Promise that was rejected.
PromiseRejectionEvent.reason Read only: A value or Object indicating why the promise was rejected, as passed to Promise.reject().

Methods

This interface has no unique methods; inherits methods from its parent Event.

Events

rejectionhandled: Fired when a JavaScript Promise is rejected, and after the rejection is handled by the promise's rejection handling code.
unhandledrejection: Fired when a JavaScript Promise is rejected but there is no rejection handler to deal with the rejection.

Examples

This simple example catches unhandled promise rejections and logs them for debugging purposes.

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

Specifications

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

Browser compatibility

	Desktop						Mobile
	Chrome	Edge	Firefox	Internet Explorer	Opera	Safari	Android webview	Chrome for Android	Firefox for Android	Opera for Android	Safari on iOS	Samsung Internet
`PromiseRejectionEvent`	Chrome Full support 49	Edge Full support ≤79	Firefox 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.	IE No support No	Opera Full support 36	Safari Full support 11	WebView Android Full support 49	Chrome Android Full support 49	Firefox 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.	Opera Android Full support 36	Safari iOS Full support 11.3	Samsung Internet Android Full support 5.0
`PromiseRejectionEvent()` constructor	Chrome Full support 49	Edge Full support ≤79	Firefox 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.	IE No support No	Opera Full support 36	Safari Full support 11	WebView Android Full support 49	Chrome Android Full support 49	Firefox 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.	Opera Android Full support 36	Safari iOS Full support 11.3	Samsung Internet Android Full support 5.0
`promise`	Chrome Full support 49	Edge Full support ≤79	Firefox 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.	IE No support No	Opera Full support 36	Safari Full support 11	WebView Android Full support 49	Chrome Android Full support 49	Firefox 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.	Opera Android Full support 36	Safari iOS Full support 11.3	Samsung Internet Android Full support 5.0
`reason`	Chrome Full support 49	Edge Full support ≤79	Firefox 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.	IE No support No	Opera Full support 36	Safari Full support 11	WebView Android Full support 49	Chrome Android Full support 49	Firefox 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.	Opera Android Full support 36	Safari iOS Full support 11.3	Samsung Internet Android Full support 5.0

Legend

Full support: Full support
No support: No support
User must explicitly enable this feature.: User must explicitly enable this feature.