counter component in react example

Example 1: simple counter react

import React, { useState } from 'react';
import ReactDOM from 'react-dom';

export const Counter = (props) => {
  const [count, setCount ] = useState(0)

  return (
    <div id="mainArea">
      button count: <span>{count}</span>
      <button id="mainButton" onClick={() => {setCount(count + 1)}}>Increase</button>
    </div>
  );

}

ReactDOM.render(
  <Counter />,
  document.getElementById('root')
);

Example 2: 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>
    )
  }
}