Function addEventListener

The error event is sent to the global scope when an unhandled error is thrown.

The default behavior when this event occurs is to print the error to the screen using console.error(), and no further application code is executed. The user must then press the + button to exit the application. Call event.preventDefault() to supress this default behavior.

See

https://developer.mozilla.org/docs/Web/API/Window/error_event

The unhandledrejection event is sent to the global scope when a JavaScript Promise that has no rejection handler is rejected.

The default behavior when this event occurs is to print the error to the screen using console.error(), and no further application code is executed. The user must then press the + button to exit the application. Call event.preventDefault() to supress this default behavior.

See

https://developer.mozilla.org/docs/Web/API/Window/unhandledrejection_event

The unload event is fired when the application is exiting.

By the time this event occurs, the event loop has already been stopped, so no async operations may be scheduled in the event handler.

See

https://developer.mozilla.org/docs/Web/API/Window/unload_event