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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

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] In Firefox, this is implemented but disabled by default. To turn it on, go to about:config and set the dom.promise_rejection_events.enabled pref to true.

See also

Document Tags and Contributors

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