Use the event name in methods like addEventListener(), or set an event handler property.

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

A Event.

PromiseRejectionEvent.promise Read only

The JavaScript Promise that was rejected.

PromiseRejectionEvent.reason Read only

A value or Promise.reject().

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

• HTMLBodyElement
• HTMLFrameSetElement
• SVGSVGElement

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,
);

• Promise rejection events
• PromiseRejectionEvent
• Promise
• unhandledrejection