How do I emit events?

Basic usage

import { AppEventBus } from '../../../core/index.js';

AppEventBus.emit('language-changed', { lang: 'fr' });

emit(event, data?) is fire-and-forget and synchronous — it calls every current subscriber immediately, in registration order, and returns void. There's no queuing or async dispatch, so a subscriber added after emit() runs won't see that call. See How do I listen to application events? for subscribing.

Typed payloads via EventMap

Events and their payloads are typed via a global EventMap, built from the framework's own FrameworkEventMap plus an AppEventMap your app extends via TypeScript declaration merging:

// src/app/globals.d.ts
declare interface AppEventMap {
  'my-event': {};
}

This merge is purely a compile-time typing mechanism — AppEventMap/EventMap are ambient interfaces, not exported values, so you can't import { AppEventMap } from anywhere. The underlying event bus isn't restricted to statically known keys at runtime; the declaration only adds type safety on top of it.

AppEventBus.emit('my-event', {}); // now type-checked against your declared payload shape
AppEventBus.emit('my-unregistered-event', {}); // payload can have any shape

See What are events in Nutin? for how this fits alongside DOM events and the Lifecycle/Navigation facades.