Window: rejectionhandled event
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 methods like addEventListener(), or set an event handler property.
addEventListener("rejectionhandled", (event) => { })
onrejectionhandled = (event) => { }
Event type
A PromiseRejectionEvent. Inherits from Event.
Event properties
PromiseRejectionEvent.promiseRead only-
The JavaScript
Promisethat was rejected. PromiseRejectionEvent.reasonRead only-
A value or
Objectindicating why the promise was rejected, as passed toPromise.reject().
Event handler aliases
In addition to the Window interface, the event handler property onrejectionhandled is also available on the following targets:
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
| Specification |
|---|
| HTML # unhandled-promise-rejections |
| HTML # handler-window-onrejectionhandled |
Browser compatibility
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