PromiseRejectionEvent.reason

The read-only PromiseRejection property reason read-only property is any JavaScript value or Object which provides the reason passed into Promise.reject(). This in theory provides information about why the promise was rejected.

Syntax

reason = PromiseRejectionEvent.reason

Value

A  value or object which provides information you can use to understand why the promise was rejected. This could be anything from an error code to an object with text, links, and whatever else you might wish to include.

Examples

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

Specifications

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

Browser compatibility

Update compatibility data on GitHub
DesktopMobile
ChromeEdgeFirefoxInternet ExplorerOperaSafariAndroid webviewChrome for AndroidEdge MobileFirefox for AndroidOpera for AndroidSafari on iOSSamsung Internet
Basic supportChrome Full support 49Edge ? Firefox No support No
Notes Disabled
No support No
Notes Disabled
Notes Firefox doesn't yet send the unhandledrejection or understand rejectionhandled events. Completing the implementation will be addressed in bug 1362272.
Disabled 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 No support NoSafari No support NoWebView Android ? Chrome Android No support NoEdge Mobile ? Firefox Android No support No
Notes Disabled
No support No
Notes Disabled
Notes Firefox doesn't yet send the unhandledrejection or understand rejectionhandled events. Completing the implementation will be addressed in bug 1362272.
Disabled 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 No support NoSamsung Internet Android ?

Legend

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

See also

Document Tags and Contributors

Contributors to this page: fscholz, Sheppy, chrisdavidmills
Last updated by: fscholz,