function in react js code example

Example 1: class in react

class App extends Component {
    constructor() {
        super()
        this.state = {
            name: "Sally",
            age: 13
        }
    }
    
    render() {
        return (
            

                
{this.state.name}
                
{this.state.age} years old
            
        )    
    }
}

Example 2: react bind function to component

class Foo extends Component {
  constructor(props) {
    super(props);
    this.handleClick = this.handleClick.bind(this);
  }
  handleClick() {
    console.log('Click happened');
  }
  render() {
    return Click Me;
  }
}

Example 3: create react component class

class MyComponent extends React.Component{
    constructor(props){
        super(props);
    };
    render(){
        return(
            

              

              	My First React Component!
              
            
        );
    }
};

Example 4: react functional components

const component = () => {
console.log("This is a functional Component");
}

Example 5: defining functions in 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 ;
    }
}

Example 6: callback in react

import React, { useCallback } from 'react';

function MyComponent() {
  // handleClick is the same function object
  const handleClick = useCallback(() => {    console.log('Clicked!');  }, []);
  // ...
}