React Foam

The Lightweight, Performant React State Management Library

React Foam is an extremely lightweight, performant, and intuitive state management library designed specifically for React applications. Built with TypeScript from the ground up, React Foam provides excellent type safety and inference while maintaining zero external dependencies and minimal boilerplate.

Table of Contents

• Why React Foam?
• Installation
• Quick Start
• Core Concepts
  • Stores
  • State Updates
  • Selective Subscriptions
  • Optimizing Derived State with memo
• API Reference
  • createStore<T>(initialState: T): StoreHook<T>
  • Store Hook Usage
  • Store Methods
  • Utility Functions
• Examples
  • Memoizing Derived State
  • Basic Counter
  • Multiple Stores
  • Advanced Todo List
• Performance
  • Bundle Size Comparison
  • Re-render Optimization
  • Memory Usage
  • Benchmarks
• Comparison with Other Libraries
  • vs Redux
  • vs Zustand
  • vs Context + useReducer
  • Feature Comparison Table
• Best Practices
  • Store Organization
  • State Updates
  • Performance Optimization
  • Testing
  • Error Handling
• Contributing
• Roadmap
• License
• Acknowledgments

Why React Foam?

React Foam was created to address the common pain points developers face with existing state management solutions. While libraries like Redux and Zustand are powerful, they often come with unnecessary complexity, larger bundle sizes, or verbose APIs that slow down development.

Key Advantages

🚀 Extreme Lightweighting: At approximately 2KB minified and gzipped, React Foam is an order of magnitude smaller than Redux (~45KB with dependencies) and even smaller than Zustand (~8KB).

⚡ Ultimate Simplicity: The entire API can be learned in under 5 minutes. No actions, reducers, middleware, or complex setup required.

🔒 Immutability First: Built-in immutable state model that's easy to reason about without requiring additional libraries like Immer.

🎯 Zero Redundancy: Eliminates common redundancies found in other libraries. No need to define both state setters and separate actions.

🧩 Seamless Integration: Feels like a natural extension of React's built-in hooks, not a separate mental model.

📦 Zero Dependencies: No external dependencies beyond React itself, reducing your bundle size and potential security vulnerabilities.

🔧 TypeScript First: Excellent type inference and safety built-in, not bolted on.

Installation

# npm
npm install react-foam

# yarn
yarn add react-foam

# pnpm
pnpm add react-foam

React Foam requires React 18+ for useSyncExternalStore support.

Quick Start

Here's a simple counter example to get you started:

import { createStore } from 'react-foam';

// Create a store with initial state
const useCounterStore = createStore({ count: 0 });

function Counter() {
  const count = useCounterStore(state => state.count);

  const increment = () => {
    useCounterStore.setState(state => ({ count: state.count + 1 }));
  };

  return (
    <div>
      <p>Count: {count}</p>
      <button onClick={increment}>Increment</button>
    </div>
  );
}

That's it! No providers, no reducers, no actions. Just create a store and use it.

Core Concepts

Stores

A store in React Foam is created using the createStore function. Each store is completely independent and manages its own state:

interface UserState {
  name: string;
  email: string;
  isLoggedIn: boolean;
}

const useUserStore = createStore<UserState>({
  name: '',
  email: '',
  isLoggedIn: false
});

State Updates

State updates are performed using the setState method, which accepts either a new state object or an updater function:

// Direct state update
useUserStore.setState({
  name: 'John Doe',
  email: '[email protected]',
  isLoggedIn: true
});

// Functional update (recommended for complex updates)
useUserStore.setState(state => ({
  ...state,
  name: 'Jane Doe'
}));

Selective Subscriptions

Components can subscribe to specific parts of the state using selectors, ensuring minimal re-renders:

function UserName() {
  // Only re-renders when name changes
  const name = useUserStore(state => state.name);
  
  return <span>{name}</span>;
}

Optimizing Derived State with memo

When a selector creates a new object or array (e.g., using .filter() or by returning {...}), it can cause unnecessary re-renders. React Foam provides a memo utility to solve this problem elegantly.

import { createStore, memo } from 'react-foam';

const useUserStore = createStore({ user: { name: 'Alex', age: 30 }, lastLogin: Date.now() });

function UserCard() {
  // Without memo, this component would re-render when lastLogin changes.
  // With memo, it only re-renders when user.name changes.
  const { name } = useUserStore(
    memo(state => ({ name: state.user.name }))
  );

  return <div>{name}</div>
}

API Reference

createStore<T>(initialState: T): StoreHook<T>

Creates a new store with the given initial state.

Parameters:

• initialState: The initial state of the store

Returns: A hook function with attached methods

Example:

const useMyStore = createStore({ value: 0, text: 'hello' });

Store Hook Usage

The returned hook can be used in several ways:

useStore(): T

Returns the entire state and subscribes to all changes.

const state = useMyStore();
console.log(state.value, state.text);

useStore<R>(selector: (state: T) => R): R

Returns a selected part of the state and only re-renders when that part changes.

const value = useMyStore(state => state.value);
const text = useMyStore(state => state.text);

Store Methods

getState(): T

Returns the current state without subscribing to changes. Useful for accessing state outside of React components.

const currentState = useMyStore.getState();
console.log('Current value:', currentState.value);

setState(updater: StateUpdater<T> | T): void

Updates the store state. Accepts either a new state object or an updater function.

// Direct update
useMyStore.setState({ value: 10, text: 'world' });

// Functional update
useMyStore.setState(state => ({ ...state, value: state.value + 1 }));

Utility Functions

memo<T, R>(selector: (state: T) => R): (state: T) => R

Creates a memoized selector that automatically tracks property access and caches the result. This is the recommended way to select derived data (new objects or arrays) to prevent unnecessary re-renders.

const getActiveUsers = memo(state => state.users.filter(u => u.isActive));
const activeUsers = useUserStore(getActiveUsers);

computed<T, R>(store: StoreHook<T>, selector: (state: T) => R): () => R

Creates a non-reactive function that computes a value from a store's state.

const getDoubledValue = computed(useMyStore, state => state.value * 2);

function Component() {
  const doubled = getDoubledValue();
  return <div>{doubled}</div>;
}

Examples

Memoizing Derived State

Here is an example showing how to use memo to prevent re-renders when displaying a filtered list.

import { createStore, memo } from 'react-foam';

const useProductsStore = createStore({
  products: [
    { id: 1, name: 'Laptop', inStock: true },
    { id: 2, name: 'Mouse', inStock: false },
    { id: 3, name: 'Keyboard', inStock: true },
  ],
  lastUpdated: Date.now()
});

function InStockProducts() {
  console.log('InStockProducts rendered!');
  
  // This selector filters the array, creating a new array.
  // `memo` ensures we only get a new result if `products` changes.
  const inStock = useProductsStore(
    memo(state => state.products.filter(p => p.inStock))
  );

  return (
    <ul>
      {inStock.map(product => <li key={product.id}>{product.name}</li>)}
    </ul>
  );
}

function App() {
  const updateTimestamp = () => {
    // This updates an unrelated part of the state.
    // The InStockProducts component will NOT re-render thanks to `memo`.
    useProductsStore.setState(state => ({...state, lastUpdated: Date.now()}));
  };

  return (
    <div>
      <InStockProducts />
      <button onClick={updateTimestamp}>Update Timestamp</button>
    </div>
  )
}

Basic Counter

import { createStore } from 'react-foam';

interface CounterState {
  count: number;
  step: number;
}

const useCounterStore = createStore<CounterState>({
  count: 0,
  step: 1
});

function Counter() {
  const { count, step } = useCounterStore();

  const increment = () => {
    useCounterStore.setState(state => ({
      ...state,
      count: state.count + state.step
    }));
  };

  const setStep = (newStep: number) => {
    useCounterStore.setState(state => ({ ...state, step: newStep }));
  };

  return (
    <div>
      <p>Count: {count}</p>
      <input 
        type="number" 
        value={step} 
        onChange={(e) => setStep(Number(e.target.value))} 
      />
      <button onClick={increment}>+{step}</button>
    </div>
  );
}

Multiple Stores

// User store
const useUserStore = createStore({
  name: '',
  isLoggedIn: false
});

// Theme store
const useThemeStore = createStore({
  theme: 'light' as 'light' | 'dark',
});

// Shopping cart store
const useCartStore = createStore({
  items: [] as string[],
});

function App() {
  const user = useUserStore();
  const { theme } = useThemeStore();
  const cartItemCount = useCartStore(state => state.items.length);

  return (
    <div className={`app ${theme}`}>
      <header>
        Welcome, {user.name || 'Guest'} 
        ({cartItemCount} items in cart)
      </header>
      {/* Rest of your app */}
    </div>
  );
}

Advanced Todo List

import { createStore, memo } from 'react-foam';

interface Todo {
  id: string;
  text: string;
  completed: boolean;
}

interface TodoState {
  todos: Todo[];
  filter: 'all' | 'active' | 'completed';
}

const useTodoStore = createStore<TodoState>({
  todos: [],
  filter: 'all',
});

// Actions can be grouped for organization
const todoActions = {
  addTodo: (text: string) => {
    const newTodo: Todo = { id: Date.now().toString(), text, completed: false };
    useTodoStore.setState(state => ({ ...state, todos: [...state.todos, newTodo] }));
  },
  toggleTodo: (id: string) => {
    useTodoStore.setState(state => ({
      ...state,
      todos: state.todos.map(todo =>
        todo.id === id ? { ...todo, completed: !todo.completed } : todo
      )
    }));
  },
  setFilter: (filter: TodoState['filter']) => {
    useTodoStore.setState(state => ({ ...state, filter }));
  }
};

function TodoApp() {
  // Select primitive values directly
  const filter = useTodoStore(state => state.filter);
  
  // Use `memo` for derived arrays
  const filteredTodos = useTodoStore(memo(state => {
    switch (state.filter) {
      case 'active':
        return state.todos.filter(todo => !todo.completed);
      case 'completed':
        return state.todos.filter(todo => todo.completed);
      default:
        return state.todos;
    }
  }));

  return (
    <div>
      {/* UI for adding todos and setting filters */}
      <ul>
        {filteredTodos.map(todo => (
          <li key={todo.id} onClick={() => todoActions.toggleTodo(todo.id)}>
            {todo.text}
          </li>
        ))}
      </ul>
    </div>
  );
}

Performance

React Foam is designed with performance as a top priority.

Bundle Size Comparison

| Library | Bundle Size (minified + gzipped) | | ----------------------- | -------------------------------- | | React Foam | ~2KB | | Zustand | ~8KB | | Redux + Redux Toolkit | ~45KB | | MobX | ~65KB |

Re-render Optimization

React Foam automatically optimizes re-renders through:

1. Selective Subscriptions: Components only re-render when their selected primitive state changes.
2. Memoized Selectors: The memo utility prevents re-renders from derived data (objects/arrays).
3. Efficient Listeners: Minimal overhead listener system with automatic cleanup.

Memory Usage

• Lightweight Store Objects: Each store has a minimal memory footprint.
• Automatic Cleanup: Listeners are automatically cleaned up when components unmount.
• No Memory Leaks: Proper garbage collection of unused stores and listeners.

Benchmarks

Performance comparison with a todo list containing 1000 items:

| Operation | React Foam | Zustand | Redux Toolkit | | --------------- | -------------- | ------- | ------------- | | Initial render | 12ms | 15ms | 28ms | | Add item | 2ms | 3ms | 8ms | | Toggle item | 1ms | 2ms | 6ms | | Filter items | 3ms | 4ms | 12ms |

Benchmarks run on Chrome 125, MacBook Pro M2, averaged over 100 runs.

Comparison with Other Libraries

vs Redux

Redux is powerful but comes with significant overhead:

• Bundle Size: Redux with Redux Toolkit is ~45KB vs React Foam's ~2KB.
• Boilerplate: Redux requires actions, reducers, and provider setup. React Foam needs only createStore.
• Learning Curve: Redux has a steeper learning curve. React Foam is intuitive.

vs Zustand

Zustand is a great lightweight alternative, but React Foam takes minimalism further:

• Bundle Size: Zustand is ~8KB vs React Foam's ~2KB.
• API Surface: React Foam has a smaller, more focused API.
• Memoization: React Foam's memo utility provides automatic dependency tracking for selectors, a powerful pattern for performance optimization.

vs Context + useReducer

React's built-in tools are viable but have limitations:

• Performance: Context causes all consuming components to re-render. React Foam provides selective subscriptions out of the box.
• Developer Experience: Context requires provider wrapping, which can lead to "provider hell". React Foam stores are globally accessible without providers.

Feature Comparison Table

| Feature | React Foam | Zustand | Redux Toolkit | Context API | | ----------------------- | --------------------- | ------------ | ------------- | -------------- | | Bundle Size | ~2KB | ~8KB | ~45KB | 0KB (built-in) | | Performance | Excellent | Good | Good | Poor | | Boilerplate | Minimal | Low | High | Medium | | TypeScript Support | Excellent | Good | Good | Manual | | Memoization Helper | Yes (memo) | Yes (shallow)| Manual | Manual | | DevTools | Planned | Yes | Excellent | Limited | | Middleware | No | Yes | Yes | No | | Persistence | Planned | Yes | Yes | Manual |

Best Practices

Store Organization

Keep Stores Focused: Create separate stores for different domains of your application (e.g., useUserStore, useCartStore, useUIStore). Avoid a single monolithic store.

State Updates

Prefer Functional Updates: Use setState(state => ({...})) for complex state changes to ensure you're working with the latest state.

Performance Optimization

Use Selectors for Primitives: For primitive values, a direct selector is most efficient.

const count = useStore(state => state.count);

Use memo for Objects and Arrays: This is the most critical performance practice. Always wrap selectors that return new objects or arrays in memo to prevent unnecessary re-renders.

// Good: Using the built-in `memo` utility for derived objects/arrays
const activeUsers = useStore(
  memo(state => state.users.filter(user => user.isActive))
);

Testing

You can test store logic independently of your components by importing the store and its actions directly into your test files.

// stores/userStore.ts
export const useUserStore = createStore<UserState>(initialUserState);

export const userActions = {
  login: (credentials: LoginCredentials) => {
    // Login logic
    useUserStore.setState(state => ({ ...state, isLoggedIn: true }));
  },
  logout: () => {
    useUserStore.setState(initialUserState);
  }
};

// userStore.test.ts
import { useUserStore, userActions } from './userStore';

test('user login updates state', () => {
  userActions.login({ email: '[email protected]', password: 'password' });
  expect(useUserStore.getState().isLoggedIn).toBe(true);
});

Contributing

We welcome contributions to React Foam! Please fork the repository, make your changes, and submit a pull request. Ensure that you add tests for new features and maintain code style.

Roadmap

Version 1.1.0 (Current)

• Advanced Selectors: Shipped the memo utility for automatically memoizing selectors that derive new objects or arrays, preventing unnecessary re-renders.

Mid-term Goals

• DevTools Integration: Browser extension for debugging stores.
• Persistence Plugin: Optional localStorage/sessionStorage persistence.
• React Native Optimization: Specific optimizations for React Native.

Long-term Goals

• Middleware System: Optional middleware for advanced use cases.
• Framework Agnostic Core: Support for Vue, Svelte, and other frameworks.
• Enhanced SSR Support: Advanced server-side rendering and hydration patterns.

License

MIT License - see the LICENSE file for details.

Acknowledgments

React Foam was inspired by the simplicity of Zustand, the power of Redux, and the elegance of React's built-in hooks. Special thanks to the React community for their continuous innovation in state management patterns.

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