Web Browsers and Unhandled Rejections

Unhandled rejection tracking for web browsers

Unhandled rejection tracking for web browsers is defined in the HTML specification. At the core of unhandled rejection tracking are two events that are emitted by the globalThis object:

• unhandledrejection: This is emitted when a promise is rejected and no rejection handler is called within one turn of the event loop.

• rejectionhandled: This is emitted when a promise is rejected and a rejection handler is called after one turn of the event loop.

These two events are designed to be used together to accurately detect unhandled promise rejections. Here’s an example showing when each event is triggered: