React Hooks were introduced in version 16.8. They let you use state and lifecycle features in functional components. This changed how many people write React apps.

Why Hooks?

Before Hooks, you had to use class components to:

• Manage state
• Use lifecycle methods
• Share logic between components

Hooks made this easier by adding functions like useState and useEffect.

useState Example

import React, { useState } from 'react';

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

  return (
    <div>
      <p>You clicked {count} times</p>
      <button onClick={() => setCount(count + 1)}>
        Click me
      </button>
    </div>
  );
}

No constructor, no this, just clean and readable.

useEffect Example

import React, { useState, useEffect } from 'react';

function Timer() {
  const [seconds, setSeconds] = useState(0);

  useEffect(() => {
    const interval = setInterval(() => {
      setSeconds(prev => prev + 1);
    }, 1000);

    return () => clearInterval(interval);
  }, []);

  return <p>{seconds} seconds have passed.</p>;
}

useEffect replaces componentDidMount, componentDidUpdate, and componentWillUnmount.

Replacing a Class Component

Old class component:

class Counter extends React.Component {
  state = { count: 0 };

  render() {
    return (
      <button onClick={() => this.setState({ count: this.state.count + 1 })}>
        {this.state.count}
      </button>
    );
  }
}

Now with Hooks:

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

  return <button onClick={() => setCount(count + 1)}>{count}</button>;
}

Why This Matters

Hooks:

• Simplify code
• Avoid class boilerplate
• Make it easier to reuse logic with custom hooks

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Hooks changed the way we write React apps. They’re simple, flexible, and work well with today’s component-based design.