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}`);
});

Specifications

{{Specifications}}

Browser compatibility

{{Compat}}

See also

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