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PromiseRejectionEvent: reason property

The PromiseRejectionEvent reason read-only property is any JavaScript value or Object which provides the reason passed into Promise.reject(). This in theory provides information about why the promise was rejected.

Value

A value or object which provides information you can use to understand why the promise was rejected. This could be anything from an error code to an object with text, links, and whatever else you might wish to include.

Examples

js

window.onunhandledrejection = (e) => {
  console.log(e.reason);
};

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
reason 49 79 69 No 36 11 49 49 79 36 11.3 5.0

See also

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https://developer.mozilla.org/en-US/docs/Web/API/PromiseRejectionEvent/reason