counter in class component react code example

Example 1: counter app in react using class component

import React from 'react';

import './App.css';

// eslint-disable-next-line no-undef

export default class Parent extends React.Component{
  constructor(props){
    super();
    this.state={
      value:0
    }
  }
 
execute1(){
  this.setState({
    value:this.state.value+1
  })
}

execute2(){
  this.setState({
    value:this.state.value-1
  })
}
  render(){
    return(
      <div>
        <Child1 value={this.state.value} ></Child1>
        <Child2 value={this.state.value}></Child2>
        <button onClick={this.execute1.bind(this)}>click me</button>
        <button onClick={this.execute2.bind(this)}>click me</button>

      </div>
    )
  }
}

class Child1 extends React.Component{
  
  render(){
    return(
      <div className="modify">
        <label>{this.props.value}</label>
      </div>
    )
  }
}

class Child2 extends React.Component{
  
  render(){
    return(
      <div className="modify">
        <label>{this.props.value}</label>
      </div>
    )
  }
}

Example 2: counter composant react

import React, { useState } from 'react';

function Example() {
  // Déclare une nouvelle variable d'état, que l'on va appeler « count »  const [count, setCount] = useState(0);
  return (
    <div>
      <p>Vous avez cliqué {count} fois</p>
      <button onClick={() => setCount(count + 1)}>
        Cliquez ici
      </button>
    </div>
  );
}