Window: rejectionhandled event
Therejectionhandled event is sent to the script's global scope (usuallywindow but alsoWorker) whenever a rejected JavaScriptPromise 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 onlyThe JavaScript
Promisethat was rejected.PromiseRejectionEvent.reasonRead onlyA value or
Objectindicating why the promise was rejected, as passed toPromise.reject().
Event handler aliases
In addition to theWindow interface, the event handler propertyonrejectionhandled is also available on the following targets:
Example
You can use therejectionhandled 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
| Specification |
|---|
| HTML # unhandled-promise-rejections |
| HTML # handler-window-onrejectionhandled |