PromiseRejectionEvent()
The PromiseRejectionEvent()
constructor returns a newly created PromiseRejectionEvent
, which represents events fired when a JavaScript Promise
is rejected.
With promise rejection events, it becomes possible to detect and report promises which fail and whose failures go unnoticed. It also becomes easier to write a global handler for errors.
There are two types of PromiseRejectionEvent
: unhandledrejection
is sent by the JavaScript runtime when a promise is rejected but the rejection goes unhandled. A rejectionhandled
event is emitted if a promise is rejected but the rejection is caught by a rejection handler..
Syntax
promiseRejectionEvent = PromiseRejectionEvent(type, options);
Parameters
The PromiseRejectionEvent()
constructor also inherits parameters from Event()
.
type
-
A string representing the name of the type of the
PromiseRejectionEvent
. This is case-sensitive and should be one of"rejectionhandled"
or"unhandledrejection"
, to match the event names of the possible (non-synthetic)PromiseRejectionEvent
events that user agents can actually fire). options
-
An
Object
specifying details about the rejection which occurred:promise
-
The
Promise
that was rejected. reason
-
Any value or
Object
which represents the reason the promise was rejected. This can be anything from a numeric error code to an errorDOMString
to an object which contains detailed information describing the situation resulting in the promise being rejected.
Return value
A new PromiseRejectionEvent
configured as specified by the parameters.
Examples
This example creates a new unhandledrejection
event for the promise myPromise
with the reason being the string "My house is on fire". The reason
could just as easily be a number, or even an object with detailed information including the home address, how serious the fire is, and the phone number of an emergency contact who should be notified.
let myRejectionEvent = new PromiseRejectionEvent("unhandledrejection", { promise : myPromise, reason : "My house is on fire" });
Specifications
Browser compatibility
Desktop | Mobile | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
Chrome | Edge | Firefox | Internet Explorer | Opera | Safari | WebView Android | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | |
PromiseRejectionEvent |
49 |
79 |
69
68
|
No |
36 |
11 |
49 |
49 |
68 |
36 |
11.3 |
5.0 |
See also
© 2005–2021 MDN contributors.
Licensed under the Creative Commons Attribution-ShareAlike License v2.5 or later.
https://developer.mozilla.org/en-US/docs/Web/API/PromiseRejectionEvent/PromiseRejectionEvent