Zustand computed values

This week I’ve faced some situations with Vue’s reactive that alarmed me. I’m finding the hard way what I’ve read a couple times: reactive proxies can behave unpredictably in some situations. Too bad I’m in the middle of a project which began in Vue 3. I’m strongly considering rewriting it in React now – yes, it will be an insane amount of work, including back-end changes to return normalized objects.

But React brings its own problems. The biggest of all is certainly the raw state management.

Among all state management tools I’m evaluating, Zustand is showing to be the most promising. It’s ticking all the boxes, and the only open question so far is computed state. The best I could do was to use custom hooks, but they look rather ugly and verbose:

import create from 'zustand';
import {combine} from 'zustand/middleware';

/**
 * The store, which holds the state and the actions.
 */
const useBearStore = create(
	combine({
		bears: 0,
	},
	(set, get) => ({
		increasePopulation(): void {
			set(state => ({ bears: state.bears + 1 }));
		},
		removeAllBears(): void {
			set({ bears: 0 });
		},
	})),
);

export default useBearStore;

/**
 * Custom hook that returns a computed value.
 */
export function useBearCountPlusOne(): number {
	const bears = useBearStore(s => s.bears);
	return bears + 1;
}

Usage example in a component:

import useBearStore, {useBearCountPlusOne} from './useBearStore';

function App() {
	const increasePopulation = useBearStore(s => s.increasePopulation);
	const populationPlusOne = useBearCountPlusOne();

	return <>
		<div>Population + 1: {populationPlusOne}</div>
		<button onClick={() => increasePopulation()}>
			Increase population
		</button>
	</>;
}

If I find a way to rework these loose hooks, I think I found my way.