What a hook in React.js code example

Example 1: react hooks

class Example extends React.Component {
  constructor(props) {
    super(props);
    this.state = {
      count: 0
    };
  }

  componentDidMount() {    document.title = `You clicked ${this.state.count} times`;  }  componentDidUpdate() {    document.title = `You clicked ${this.state.count} times`;  }
  render() {
    return (
      <div>
        <p>You clicked {this.state.count} times</p>
        <button onClick={() => this.setState({ count: this.state.count + 1 })}>
          Click me
        </button>
      </div>
    );
  }
}

Example 2: react hooks

useEffect(() => {
  document.title = `You clicked ${count} times`;
}, [count]); // Only re-run the effect if count changes