how to write function in react class component code example

Example 1: class in react

class App extends Component {
    constructor() {
        super()
        this.state = {
            name: "Sally",
            age: 13
        }
    }
    
    render() {
        return (
            <div>
                <h1>{this.state.name}</h1>
                <h3>{this.state.age} years old</h3>
            </div>
        )    
    }
}

Example 2: react function component

function Welcome(props) {
  return <h1>Hello, {props.name}</h1>;
}

Example 3: function inside a class component react

export default class Archive extends React.Component { 

    saySomething(something) {
        console.log(something);
    }

    handleClick(e) {
        this.saySomething("element clicked");
    }

    componentDidMount() {
        this.saySomething("component did mount");
    }

    render() {
        return <button onClick={this.handleClick.bind(this)} value="Click me" />;
    }
}

Example 4: react native function

class Foo extends Component {
  handleClick() {
    console.log('Click happened');
  }
  render() {
    return <button onClick={this.handleClick.bind(this)}>Click Me</button>;
  }
}