PromiseRejectionEvent: PromiseRejectionEvent() constructor
Note: This feature is available in Web Workers.
The PromiseRejectionEvent()
constructor returns a new PromiseRejectionEvent object, 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
new PromiseRejectionEvent(type, options)
Parameters
type-
A string with the name of the event. It is case-sensitive and browsers set it to
rejectionhandledorunhandledrejection. options-
An object that, in addition of the properties defined in
Event(), can have the following properties:promise-
The
Promisethat was rejected. reason-
Any value or
Objectwhich represents the reason the promise was rejected. This can be anything from a numeric error code to an error string to an object which contains detailed information describing the situation resulting in the promise being rejected.
Return value
A new PromiseRejectionEvent object 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
| Specification |
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| HTML # unhandled-promise-rejections:dom-event-constructor |
Browser compatibility
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PromiseRejectionEvent() constructor
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