The rejectionhandled event is fired when a JavaScript Promise is rejected, and after the rejection is handled by the promise's rejection handling code.
| Bubbles | No | 
| Cancelable | No | 
| Target objects | defaultView | 
| Interface | PromiseRejectionEvent |  
The rejectionhandled event implements the PromiseRejectionEvent interface, which inherits from Event. You can use the properties and methods defined on these interfaces.
window.addEventListener("rejectionhandled", function (event) {
  console.log("Promise rejected! Reason: " + event.reason);
});
 | Specification | Status | Comment | 
|---|---|---|
| HTML Living Standard The definition of 'onrejectionhandled' in that specification.  |  Living Standard | Initial definition. | 
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| 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.
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Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
    https://developer.mozilla.org/en-US/docs/Web/Events/rejectionhandled