unhandledrejection

The unhandledrejection event is fired when a JavaScript Promise is rejected but there is no rejection handler to deal with the rejection.

Inheritance

The unhandledrejection event implements the PromiseRejectionEvent interface, which inherits from Event. You can use the properties and methods defined on these interfaces.

Examples

Simple Reporting

window.addEventListener("unhandledrejection", function (event) {
    console.warn("WARNING: Unhandled promise rejection. Shame on you! Reason: "
                 + event.reason);
});

Preventing Default

Many environments report unhandled promise rejections to the console by default. The event is cancelable, and so preventDefault prevents that default action:

window.addEventListener("unhandledrejection", function (event) {
    // ...your code here to handle the unhandled rejection...

    // Prevent the default handling (error in console)
    event.preventDefault();
});

Specifications

Browser compatibility

We're converting our compatibility data into a machine-readable JSON format. This compatibility table still uses the old format, because we haven't yet converted the data it contains. Find out how you can help!

See also

• rejectionhandled
• PromiseRejectionEvent
• Promise