React API Reference
The React API Reference is a comprehensive guide to all core React methods, components, and hooks, providing developers with the essential tools to build modern, scalable web applications. Understanding the React API is crucial for developing high-performance single-page applications (SPAs) and ensuring maintainable, reusable components. It allows developers to manage state efficiently, handle data flow, and control the lifecycle of components, which are foundational to React’s component-based architecture.
Using the React API Reference is essential when implementing complex functionality, optimizing performance, and avoiding common mistakes like prop drilling, unnecessary re-renders, or direct state mutations. Developers will learn how to use functional components, class components, and hooks such as useState, useEffect, and useReducer to manage both simple and complex state logic. Additionally, the reference provides patterns for building reusable components, managing side effects, and integrating React features into modern web applications. By following this reference, readers will gain practical knowledge to efficiently build interactive UIs, improve application performance, and apply advanced React best practices in real-world projects.
Basic Example
jsximport React, { useState } from 'react';
function Counter() {
const [count, setCount] = useState(0);
const increment = () => setCount(prev => prev + 1);
const decrement = () => setCount(prev => prev - 1);
return ( <div> <h1>Counter: {count}</h1> <button onClick={increment}>Increase</button> <button onClick={decrement}>Decrease</button> </div>
);
}
export default Counter;This basic Counter component demonstrates fundamental React API concepts, including state management with useState. The useState hook provides a state variable, count, and an updater function, setCount. Using the previous state in setCount ensures safe updates, preventing common issues from direct state mutations. The increment and decrement functions are attached to button onClick events, allowing interactive updates.
This example highlights React’s automatic re-rendering on state changes, which keeps the UI synchronized with the underlying state. It also reinforces best practices by maintaining local state within the component, avoiding prop drilling and unnecessary complexity. For beginners, it illustrates how React abstracts direct DOM manipulation, simplifying dynamic UI development. This foundation is critical for more advanced patterns, such as handling complex state, side effects, and integrating reusable components in larger applications.
Practical Example
jsximport React, { useState, useEffect } from 'react';
function TodoList() {
const [todos, setTodos] = useState([]);
const [input, setInput] = useState('');
const addTodo = () => {
if (input.trim() !== '') {
setTodos(prev => [...prev, input]);
setInput('');
}
};
useEffect(() => {
console.log('Todos updated:', todos);
}, [todos]);
return ( <div> <h2>Todo List</h2>
<input
type="text"
value={input}
onChange={e => setInput(e.target.value)}
placeholder="Add a new task"
/> <button onClick={addTodo}>Add</button> <ul>
{todos.map((todo, index) => ( <li key={index}>{todo}</li>
))} </ul> </div>
);
}
export default TodoList;Advanced React Implementation
jsximport React, { useState, useEffect, useCallback } from 'react';
function OptimizedTodoList() {
const [todos, setTodos] = useState([]);
const [input, setInput] = useState('');
const addTodo = useCallback(() => {
if (input.trim() !== '') {
setTodos(prev => [...prev, input]);
setInput('');
}
}, [input]);
useEffect(() => {
console.log('Optimized Todo List updated:', todos);
}, [todos]);
return ( <div> <h2>Optimized Todo List</h2>
<input
type="text"
value={input}
onChange={e => setInput(e.target.value)}
placeholder="Add a new task"
/> <button onClick={addTodo}>Add</button> <ul>
{todos.map((todo, index) => ( <li key={index}>{todo}</li>
))} </ul> </div>
);
}
export default OptimizedTodoList;In the advanced example, OptimizedTodoList uses useCallback to memoize the addTodo function, preventing unnecessary re-renders of child components when props change. The useEffect hook monitors the todos state for updates, demonstrating lifecycle handling and side effect management.
React best practices include breaking components into reusable units, using hooks efficiently for state management, leveraging Context API to avoid prop drilling, and optimizing rendering with React.memo, useCallback, and useMemo. Common pitfalls include directly mutating state, excessive re-renders, and deeply nested props. React DevTools provides debugging capabilities to trace state and rendering issues. Security considerations involve avoiding dangerouslySetInnerHTML without sanitization and using unique keys in lists to prevent rendering issues and performance degradation. Following these practices ensures scalable, maintainable, and high-performance SPAs.
📊 Comprehensive Reference
| React Element/Method | Description | Syntax | Example | Notes |
|---|---|---|---|---|
| useState | Manage local state in functional components | const [state, setState] = useState(initial) | const [count, setCount] = useState(0); | Ideal for simple state |
| useEffect | Handle side effects and lifecycle | useEffect(() => {}, [dependencies]); | useEffect(() => { console.log(count); }, [count]); | Runs after render |
| useContext | Consume context values | const value = useContext(Context); | const theme = useContext(ThemeContext); | Avoids prop drilling |
| useReducer | Manage complex state | const [state, dispatch] = useReducer(reducer, initial) | const [state, dispatch] = useReducer(todoReducer, []); | Suitable for complex logic |
| React.memo | Prevent unnecessary re-renders | export default React.memo(Component); | export default React.memo(TodoItem); | Re-renders only when props change |
| useCallback | Memoize functions | const memoizedFn = useCallback(fn, [dependencies]); | const addTodo = useCallback(() => {}, [todos]); | Optimizes child props |
| useRef | Create refs | const ref = useRef(initial); | const inputRef = useRef(); | Access DOM or store mutable values |
| useLayoutEffect | Run effect before render | useLayoutEffect(() => {}, [dependencies]); | useLayoutEffect(() => {}, []); | Synchronous with DOM updates |
| createContext | Create context for sharing data | const Context = createContext(defaultValue); | const ThemeContext = createContext('light'); | Useful for global state |
| forwardRef | Forward refs to child components | const Component = forwardRef((props, ref) => {}); | const Input = forwardRef((props, ref) => <input ref={ref} />); | Allows parent to access child ref |
📊 Complete React Properties Reference
| Property | Values | Default | Description | React Support |
|---|---|---|---|---|
| className | string | '' | Assign CSS classes to component | All React versions |
| key | string | null | Unique identifier for list elements | All React versions |
| ref | object | null | Reference to component or DOM element | 16.3+ |
| children | node | null | Child elements of component | All React versions |
| style | object | {} | Inline styles | All React versions |
| dangerouslySetInnerHTML | object | null | Insert raw HTML | All React versions |
| defaultValue | string | '' | Default value for form elements | All React versions |
| defaultChecked | boolean | false | Default checked state for checkbox | All React versions |
| onClick | function | null | Handle click events | All React versions |
| onChange | function | null | Handle input changes | All React versions |
The React API Reference equips developers with knowledge to efficiently manage component state, data flow, and lifecycle, enhancing both performance and maintainability. Mastering this reference lays the groundwork for advanced topics such as custom hooks, state management libraries like Redux or Zustand, and large-scale SPA optimization. Continuous practice, combined with official documentation and community best practices, ensures developers can confidently implement React API patterns in production-grade applications.
🧠 Test Your Knowledge
Test Your Knowledge
Challenge yourself with this interactive quiz and see how well you understand the topic
📝 Instructions
- Read each question carefully
- Select the best answer for each question
- You can retake the quiz as many times as you want
- Your progress will be shown at the top