Window: rejectionhandled event

{{APIRef("HTML DOM")}} 

The rejectionhandled event is sent to the script’s global scope (usually {{domxref("window")}}  but also {{domxref("Worker")}} ) whenever a rejected JavaScript {{jsxref("Promise")}}  is handled late, i.e. when a handler is attached to the promise after its rejection had caused an {{domxref("Window.unhandledrejection_event", "unhandledrejection")}}  event.

This can be used in debugging and for general application resiliency, in tandem with the unhandledrejection event, which is sent when a promise is rejected but there is no handler for the rejection at the time.

Syntax

Use the event name in methods like {{domxref("EventTarget.addEventListener", "addEventListener()")}} , or set an event handler property.

addEventListener("rejectionhandled", (event) => {});
onrejectionhandled = (event) => {};

Event type

A {{domxref("PromiseRejectionEvent")}} . Inherits from {{domxref("Event")}} .

{{InheritanceDiagram("PromiseRejectionEvent")}} 

Event properties

• {{domxref("PromiseRejectionEvent.promise")}}  {{ReadOnlyInline}} 
  • : The JavaScript {{jsxref("Promise")}}  that was rejected.
• {{domxref("PromiseRejectionEvent.reason")}}  {{ReadOnlyInline}} 
  • : A value or {{jsxref("Object")}}  indicating why the promise was rejected, as passed to {{jsxref("Promise.reject()")}} .

Event handler aliases

In addition to the Window interface, the event handler property onrejectionhandled is also available on the following targets:

• {{domxref("HTMLBodyElement")}} 
• {{domxref("HTMLFrameSetElement")}} 
• {{domxref("SVGSVGElement")}} 

Example

You can use the rejectionhandled event to log promises that get rejected to the console, along with the reasons why they were rejected:

window.addEventListener(
  "rejectionhandled",
  (event) => {
    console.log(`Promise rejected; reason: ${event.reason}`);
  },
  false,
);

Specifications

{{Specifications}} 

Browser compatibility

{{Compat}} 

See also

• Promise rejection events
• {{domxref("PromiseRejectionEvent")}} 
• {{jsxref("Promise")}} 
• {{domxref("Window/unhandledrejection_event", "unhandledrejection")}}