Zustand Storeの作成
Zustandをインストールし、createでstoreを定義してstateプロパティとアクション関数を追加し、storeがReduxアーキテクチャとどう異なるかを理解します
「Zustand Storeの作成」はCoddyKit上の無料React Native Academyレッスンです。 これはレッスン1/4です。 下記で完全なレッスンを無料で読むことができます。その後、ブラウザ内の組み込みコードエディタと24時間対応のAIチューターでハンズオン演習できます。 これはReact Native Academy学習パスの一部であり、ウェブとCoddyKitアプリ全体で進捗が同期されます。 React Native Academyコースには全4レッスンが含まれています。
このレッスンの一部はまだ翻訳されておらず、英語で表示されています。
What Is Zustand?
Zustand (German for 'state') is a minimal, fast state management library for React. Unlike Redux, it requires no boilerplate like action creators, reducers, or a Provider wrapper. You define a store as a single function, and any component can subscribe to it with a simple hook. It is ideal for apps that need global state without the complexity of Redux Toolkit.
Installing Zustand
Install Zustand from npm with a single command. It has zero dependencies and is compatible with React Native out of the box. The package is lightweight — under 1 kB gzipped — which keeps your app's bundle size small.
npm install zustandCreating Your First Store
Call create from Zustand and pass it a function that receives set and returns an object containing your state properties and actions. The returned value is a custom hook — conventionally named useXxxStore — that components call to access the store.
import { create } from 'zustand';
interface CounterStore {
count: number;
increment: () => void;
decrement: () => void;
reset: () => void;
}
export const useCounterStore = create<CounterStore>((set) => ({
count: 0,
increment: () => set((state) => ({ count: state.count + 1 })),
decrement: () => set((state) => ({ count: state.count - 1 })),
reset: () => set({ count: 0 }),
}));The set Function
The set function is how Zustand updates state. You can pass it either a partial state object (Zustand merges it with existing state) or a callback that receives the current state and returns the updated portion. Zustand automatically notifies all subscribers when state changes.
// Partial object — Zustand merges it
set({ count: 0 });
// Callback — use when new value depends on previous value
set((state) => ({ count: state.count + 1 }));
// Replace entire state (pass true as second arg)
set(() => ({ count: 0, name: 'reset' }), true);No Provider Needed
One of Zustand's biggest advantages over Redux is that you do not need to wrap your component tree in a Provider. The store lives outside React and components subscribe to it directly via the returned hook. This means you can use the store anywhere — in components, in callbacks, or even outside React components.
// No Provider needed — just use the hook anywhere
function CounterDisplay() {
const count = useCounterStore((state) => state.count);
return <Text>Count: {count}</Text>;
}
function CounterButtons() {
const increment = useCounterStore((state) => state.increment);
const decrement = useCounterStore((state) => state.decrement);
return (
<View>
<Button title='+' onPress={increment} />
<Button title='-' onPress={decrement} />
</View>
);
}Subscribing to Specific State
Pass a selector function to the store hook to subscribe to only part of the state. The component re-renders only when the selected value changes. Without a selector, the component re-renders whenever any part of the store updates, which can hurt performance in large stores.
// Only re-renders when count changes
const count = useCounterStore((state) => state.count);
// Only re-renders when user.name changes
const username = useUserStore((state) => state.user.name);
// Without selector — re-renders on ANY store change (avoid this)
const everything = useCounterStore();Accessing the Store Outside React
Zustand stores expose a getState() method that reads the current state synchronously without hooks. There is also a subscribe() method for non-React subscriptions and a setState() method for imperative updates. This is useful in utility functions, API interceptors, or navigation helpers that run outside React component lifecycle.
// Access store state anywhere — no hooks required
import { useCounterStore } from './counterStore';
// Read state outside React
const currentCount = useCounterStore.getState().count;
// Update state outside React
useCounterStore.getState().increment();
// Subscribe outside React
const unsub = useCounterStore.subscribe((state) => {
console.log('Count changed to:', state.count);
});Async Actions in Zustand
Zustand actions can be async — just mark the function async and call set after the await. You do not need special async utilities like Redux's createAsyncThunk. You can add loading and error state directly to the store and update them inside the async action.
export const usePostsStore = create<PostsStore>((set) => ({
posts: [],
loading: false,
error: null,
fetchPosts: async () => {
set({ loading: true, error: null });
try {
const res = await fetch('https://api.example.com/posts');
const data = await res.json();
set({ posts: data, loading: false });
} catch (e) {
set({ error: 'Failed to load', loading: false });
}
},
}));Comparing Zustand and Redux
Redux Toolkit is more structured and provides stronger conventions for large teams, time-travel debugging, and complex state. Zustand excels when you need global state with minimal ceremony — a single file, no action types, no Provider. Both are valid choices; pick Zustand for small-to-medium apps or when you want to move fast without Redux boilerplate.
Organizing Multiple Stores
In larger apps, split your state into multiple focused stores rather than one massive store. For example, create useAuthStore, useCartStore, and useSettingsStore separately. Each store file is small, independently testable, and imported only by the components that need it. This prevents unrelated state changes from triggering unnecessary re-renders.
// stores/authStore.ts
export const useAuthStore = create<AuthStore>((set) => ({ /* ... */ }));
// stores/cartStore.ts
export const useCartStore = create<CartStore>((set) => ({ /* ... */ }));
// Component imports only what it needs
import { useAuthStore } from '../stores/authStore';
import { useCartStore } from '../stores/cartStore';Immer Middleware for Complex Updates
If your state is deeply nested and you want mutating-style updates (like Redux Toolkit's Immer integration), wrap the store creator with Zustand's immer middleware. With Immer, you can write state.user.preferences.theme = 'dark' instead of spreading every level of the object manually.
import { create } from 'zustand';
import { immer } from 'zustand/middleware/immer';
export const useSettingsStore = create(immer<SettingsStore>((set) => ({
user: { name: '', preferences: { theme: 'light', notifications: true } },
setTheme: (theme) => set((state) => {
state.user.preferences.theme = theme; // Immer makes this safe
}),
})));Quick Check
Test your understanding of React Native Mobile Development concepts from this lesson.
Lesson Recap
In this lesson you learned: Zustand creates global stores with minimal boilerplate using a single create call, no Provider is required because the store lives outside the React tree, and async actions work natively by marking store functions as async. Next up we explore reading and updating Zustand store state in components.
よくある質問
「Zustand Storeの作成」レッスンは無料ですか？
はい。「Zustand Storeの作成」の完全なテキストはこのウェブで無料で読めます。インタラクティブに演習し（組み込みコードエディタと24時間対応のAIチューター）、React Native Academyコースの残りをアンロックするには、CoddyKit PROにアップグレードしてください。 React Native Academyコースには全4レッスンが含まれています。
「Zustand Storeの作成」で何を学びますか？
Zustandをインストールし、createでstoreを定義してstateプロパティとアクション関数を追加し、storeがReduxアーキテクチャとどう異なるかを理解します ブラウザで直接実行するハンズオンコードでReact Native Academyを演習し、24時間対応のAIチューターがレッスンを進める中での質問に答えます。
React Native Academyを始めるのに経験は必要ですか？
事前経験は必要ありません。CoddyKitのReact Native Academyは初級者から上級者向けに構成されているため、ここから始めるか最初から始めて、自分のペースで進むことができます。 これはレッスン1/4です。
「Zustand Storeの作成」レッスンにはどのくらい時間がかかりますか？
ほとんどのCoddyKitレッスンは約5～10分かかります。各レッスンはコンパクトでインタラクティブなので、着実に進歩し、ウェブとアプリ全体で正確に前回の場所から再開できます。
このReact Native Academyレッスンでコードを書いて実行できますか？
はい。すべてのReact Native Academyレッスンに組み込みコードエディタが含まれているため、ブラウザでリアルコードを書いて実行し、即座のAIフィードバックを取得できます。ローカル設定は不要です。