Therejectionhandled event is sent to the script's global scope (typicallyWorkerGlobalScope) whenever a rejectedPromise is handled late, i.e., when a handler is attached to the promise after its rejection had caused anunhandledrejection event.

This can be used in debugging and for general application resiliency, in tandem with theunhandledrejection 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 likeaddEventListener(), or set an event handler property.

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

Event type

APromiseRejectionEvent. Inherits fromEvent.

Event properties

PromiseRejectionEvent.promiseRead only

ThePromise that was rejected.

PromiseRejectionEvent.reasonRead only

A value orObject indicating why the promise was rejected, as passed toPromise.reject().

Example

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

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

Specifications

Browser compatibility

See also

• Promise rejection events
• PromiseRejectionEvent
• Promise
• unhandledrejection