Architecting a Global 'Event Bus' in Vue 3: Alternatives to the Removed $on/$off

Since Vue 3 removed the internal event emitter API, architectural patterns now favor external libraries like 'mitt' or using a Pinia-based notification store.

In Vue 2, many developers used a Vue instance as a global bus. In Vue 3, the recommended approach is decoupling. For strictly event-driven logic (like a global 'Toast' trigger from a JS utility file), libraries like mitt provide a 200-byte emitter. However, for most architectural needs, a 'Command Pattern' via Pinia is superior: an action is dispatched to a store, and interested components 'watch' a state change in that store. This provides a clear audit trail in DevTools.