Complete Guide to React Hooks

React Hooks transformed how we write React components. This guide covers everything you need to know about hooks.

useState

Manage component state:

const [count, setCount] = useState(0);

function increment() {
  setCount(count + 1);
}

useEffect

Handle side effects:

useEffect(() => {
  document.title = `Count: ${count}`;

  return () => {
    // Cleanup
  };
}, [count]);

useContext

Access context values:

const theme = useContext(ThemeContext);

useReducer

Manage complex state:

const [state, dispatch] = useReducer(reducer, initialState);

useMemo and useCallback

Optimize performance:

const memoizedValue = useMemo(() => computeExpensiveValue(a, b), [a, b]);
const memoizedCallback = useCallback(() => doSomething(a, b), [a, b]);

Custom Hooks

Create reusable logic:

function useLocalStorage(key, initialValue) {
  const [value, setValue] = useState(() => {
    const stored = localStorage.getItem(key);
    return stored ? JSON.parse(stored) : initialValue;
  });

  useEffect(() => {
    localStorage.setItem(key, JSON.stringify(value));
  }, [key, value]);

  return [value, setValue];
}

Best Practices

1. Always declare hooks at the top level
2. Only call hooks from React functions
3. Use the ESLint plugin for hooks
4. Keep effects focused and simple
5. Memoize expensive computations

Conclusion

React Hooks are powerful tools that make functional components as capable as class components while being more composable and reusable.