useEffect Hook in ReactJs

 App.js:

import React from 'react';

import { useState } from 'react';

import { useEffect } from 'react';

import './App.css'

function App()

{

  const [count, setCount]=useState(0)

  useEffect(()=>{console.warn("useEffect")})

 return(

  <div className='App'>

    <h1>useEffect in React {count}</h1>

    <button onClick={()=>setCount(count+1)}>Update Counter</button>

  </div>

 )

}

export default App;