The rejectionhandled event is sent to the script's global scope (usually window but also Worker) whenever a rejected JavaScript Promise is handled late, i.e., when a handler is attached to the promise after its rejection had caused an 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 addEventListener():

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

Alternatively, assign to the event handler property of the interface:

onrejectionhandled = (event) => { }

Event type

A PromiseRejectionEvent. Inherits from Event.

Event handler aliases

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

• HTMLBodyElement
• HTMLFrameSetElement
• 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

Browser compatibility

See also

• Promise rejection events
• PromiseRejectionEvent
• Promise
• unhandledrejection