The Window.onunhandledrejection property is an event handler for processing unhandledrejection events, which are raised for unhandled Promise rejections.


window.addEventListener("unhandledrejection", function(event) { ... });
window.onunhandledrejection = function(event) { ...};

The event received by the event handler is a PromiseRejectionEvent.


window.onunhandledrejection = function(e) {


Specification Status Comment
WHATWG HTML Living Standard
The definition of 'onunhandledrejection' 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.

Document Tags and Contributors

 Contributors to this page: chrisdavidmills, Sheppy, teoli, rolfedh, jpmedley
 Last updated by: chrisdavidmills,