Event capturing and bubbling and much more

I often imagine state and events as the two impulses that drive an application. I like React a lot, but a common pitfall is that it is 95% focused on state, and so you get odd cases where you end up trying to encode events as state.

You’ll see this anywhere you see a usePrevious-like hook that you then use to determine if something changed and act on it (eg. I hold state that a robot is offline, but I want to do something special when a robot goes offline). This is inferring an event from state.

I’ve had luck adding an event bus as a core driver of a complex react application for events I don’t want to track as state. But it always feels that it’s a bit in conflict with the state-driven nature of the application.

Using Svelte and building global state classes with $state(), $effect() has really helped with managing side-effects and surgical updates without building a custom event system which has historically added unnecessary boilerplate to many of my projects with a frontend.

Having components bound to or using any of the $states or $derived update automatically without having to manually register event listeners, firing events, etc.

Used to dislike runes so much initially, but working a bit more deeply with them has really made me appreciate the API changes.