App.js

App.js

import React, { useState, useEffect } from 'react'
import logo from './logo.svg';
import './App.css';
import LoadingScreen from './loading'


function App() {
  const [loading, setLoading] = useState(true)

  useEffect(() => {
    setTimeout(() => setLoading(false), 6000)
  }, [])

  return (
    <>
    {loading === false ? (
    <div className="App">
      <header className="App-header">
        <img src={logo} className="App-logo" alt="logo" />
        <p>
          Edit <code>src/App.js</code> and save to reload.
        </p>
        <a
          className="App-link"
          href="https://reactjs.org"
          target="_blank"
          rel="noopener noreferrer"
        >
          Learn React
        </a>
      </header>
    </div>
      ) : (
        <LoadingScreen />
      )}
      </>
  );
}

export default App;

May be simpler to do loading === true ? <Loading /> : <div>...</div> (or even better: loading ? <Loading /> : <div>...</div>)