PromiseRejectionEvent: promise property

Note: This feature is available in Web Workers.

The PromiseRejectionEvent interface's promise read-only property indicates the JavaScript Promise which was rejected. You can examine the event's PromiseRejectionEvent.reason property to learn why the promise was rejected.

Value

The JavaScript Promise which was rejected, and whose rejection went unhandled.

Examples

This example listens for unhandled promises and, if the reason is an object with a code field containing the text "Module not ready", it sets up an idle callback that will retry the task that failed to execute correctly.

event.preventDefault() is called to indicate that the promise has now been handled.

js
window.onunhandledrejection = (event) => {
  if (event.reason?.code === "Module not ready") {
    requestIdleCallback((deadline) => {
      loadModule(event.reason.moduleName).then(performStartup);
    });
    event.preventDefault();
  }
};

Specifications

Specification
HTML Standard
# dom-promiserejectionevent-promise

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobileserver
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
Deno
promise

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also