Zustand as lightweight alternative in React Native

Introduction

Zustand helps you manage app data simply and fast without extra complexity.

You want to share data between screens without passing props everywhere.

Your app needs a small and easy way to remember user choices or settings.

You want to avoid complicated setup for state management.

You want a fast and simple tool that works well with React Native.

You want to keep your app code clean and easy to understand.

Syntax

React Native

import create from 'zustand'

const useStore = create(set => ({
  count: 0,
  increase: () => set(state => ({ count: state.count + 1 })),
  decrease: () => set(state => ({ count: state.count - 1 }))
}))

create makes a store to hold your app data.

Inside, you define state variables and functions to change them.

Examples

This store holds a name and a function to update it.

React Native

const useStore = create(set => ({
  name: 'Guest',
  setName: (newName) => set({ name: newName })
}))

This store manages a list of tasks and adds new ones.

React Native

const useStore = create(set => ({
  todos: [],
  addTodo: (todo) => set(state => ({ todos: [...state.todos, todo] }))
}))

Sample App

This React Native app shows a number and two buttons to add or subtract from it. Zustand keeps the number state simple and shared inside the app.

React Native

import React from 'react'
import { View, Text, Button } from 'react-native'
import create from 'zustand'

const useStore = create(set => ({
  count: 0,
  increase: () => set(state => ({ count: state.count + 1 })),
  decrease: () => set(state => ({ count: state.count - 1 }))
}))

export default function Counter() {
  const { count, increase, decrease } = useStore()

  return (
    <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
      <Text style={{ fontSize: 48, marginBottom: 20 }} accessibilityLabel="Current count">{count}</Text>
      <View style={{ flexDirection: 'row', gap: 20 }}>
        <Button title="-" onPress={decrease} accessibilityLabel="Decrease count" />
        <Button title="+" onPress={increase} accessibilityLabel="Increase count" />
      </View>
    </View>
  )
}

Important Notes

Zustand is very small and fast, so it won't slow your app.

You can use Zustand with React Native without extra setup like Redux.

Remember to keep your state simple and only store what you need.

Summary

Zustand is a simple tool to manage app data in React Native.

It uses a store with state and functions to update it.

It helps keep your app code clean and easy to maintain.

Practice

1. What is the main purpose of Zustand in React Native apps?

easy

A. To manage app state in a simple and lightweight way

B. To create complex animations

C. To handle network requests

D. To style components with CSS

Solution

1. Step 1: Understand Zustand's role

   Zustand is designed to manage state, which means keeping track of data that changes in the app.

2. Step 2: Compare options to Zustand's purpose

   Options B, C, and D relate to animations, network, and styling, which are not Zustand's focus.

3. Final Answer:

   To manage app state in a simple and lightweight way -> Option A

4. Quick Check:

   Zustand = simple state management [OK]

Hint: Zustand is about state, not styling or animations [OK]

Common Mistakes:

• Confusing Zustand with animation libraries
• Thinking Zustand handles network calls
• Assuming Zustand is for styling

2. Which of the following is the correct way to create a Zustand store in React Native?

easy

A. const useStore = new Store({ count: 0, increment: () => count++ })

B. const useStore = create(set => ({ count: 0, increment: () => set(state => ({ count: state.count + 1 })) }))

C. const useStore = createStore({ count: 0, increment() { count++ } })

D. const useStore = createStore(() => ({ count: 0, increment: () => count++ }))

Solution

1. Step 1: Recall Zustand store syntax

   Zustand uses the create function with a callback that receives set to update state.

2. Step 2: Check each option's syntax

   const useStore = create(set => ({ count: 0, increment: () => set(state => ({ count: state.count + 1 })) })) matches Zustand's pattern with create and set. Options A, B, and D use incorrect functions or syntax.

3. Final Answer:

   const useStore = create(set => ({ count: 0, increment: () => set(state => ({ count: state.count + 1 })) })) -> Option B

4. Quick Check:

   Use create with set callback = const useStore = create(set => ({ count: 0, increment: () => set(state => ({ count: state.count + 1 })) })) [OK]

Hint: Zustand store uses create() with set callback [OK]

Common Mistakes:

• Using createStore instead of create
• Not passing set function
• Incorrect increment function syntax

3. Given this Zustand store code:

const useStore = create(set => ({ count: 0, increment: () => set(state => ({ count: state.count + 1 })) }))

function Counter() {
  const count = useStore(state => state.count)
  const increment = useStore(state => state.increment)
  increment()
  return {count}
}

What will be displayed when Counter renders?

medium

A. undefined

B. 1

C. 0

D. Error

Solution

1. Step 1: Understand state updates in render

   The increment function is called inside the component body, but React state updates are asynchronous and won't reflect immediately in the same render.

2. Step 2: Determine displayed count value

   Since increment updates state after render, the displayed count remains the initial 0 during this render.

3. Final Answer:

   0 -> Option C

4. Quick Check:

   State updates async, initial render shows 0 [OK]

Hint: State changes don't show immediately in same render [OK]

Common Mistakes:

• Assuming increment updates count instantly
• Expecting count to be 1 immediately
• Confusing state update timing

4. Identify the error in this Zustand store code:

const useStore = create(set => ({
  count: 0,
  increment: () => set({ count: count + 1 })
}))

medium

A. Using count without accessing state inside set

B. Missing initial count value

C. Using arrow function incorrectly

D. Not returning an object from create

Solution

1. Step 1: Check how count is used in set

   The increment function uses count directly, but count is not defined in that scope; it should access state.count.

2. Step 2: Correct usage of set with state

   set should receive a function with state parameter to get current count: set(state => ({ count: state.count + 1 })).

3. Final Answer:

   Using count without accessing state inside set -> Option A

4. Quick Check:

   Access state.count inside set callback [OK]

Hint: Use set(state => ...) to access current state [OK]

Common Mistakes:

• Using count variable directly instead of state.count
• Not passing function to set
• Ignoring state parameter in set callback

5. You want to add a reset function to this Zustand store that sets count back to zero. Which is the correct way?

const useStore = create(set => ({
  count: 0,
  increment: () => set(state => ({ count: state.count + 1 })),
  reset: ???
}))

hard

A. () => set(state => ({ count: null }))

B. () => set({ count: state.count - state.count })

C. () => set({ count: state.count * 0 })

D. () => set({ count: 0 })

Solution

1. Step 1: Understand reset goal

   The reset function should set count directly to zero, ignoring current state.

2. Step 2: Evaluate each option

   () => set(state => ({ count: null })) sets count to null (wrong). Options B and C reference state.count directly in set({ ... }) but state is undefined there (error). () => set({ count: 0 }) correctly sets { count: 0 } directly.

3. Final Answer:

   () => set({ count: 0 }) -> Option D

4. Quick Check:

   Reset sets count directly to zero [OK]

Hint: Reset sets count directly to 0 without state calculation [OK]

Common Mistakes:

• Using calculations instead of direct assignment
• Setting count to null instead of zero
• Overcomplicating reset function