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
Feature | Chrome | Firefox (Gecko) | Internet Explorer | Opera | Safari |
---|---|---|---|---|---|
Basic support | 49 | No support[1] | No support | No support | No support |
Feature | Android | Firefox Mobile (Gecko) | IE Mobile | Opera Mobile | Safari Mobile |
---|---|---|---|---|---|
Basic support | No support | No support[1] | No support | No support | No support |
[1] Firefox implements the PromiseRejectionEvent
interface if you go to about:config and set the dom.promise_rejection_events.enabled
pref to true
. However, Firefox doesn't yet actually send the unhandledrejection
or understand rejectionhandled
events. Completing the implementation will be addressed in bug 1362272.