Answers for "import { useHistory } from "react-router-dom"; function App() { let history = useHistory(); }"

usehistory example

import { useHistory } from 'react-router-dom';

function Home() {
  const history = useHistory();
  return <button onClick={() => history.push('/profile')}>Profile</button>;
}

useHistory react-router-dom

In react-router-dom version 6 
useHistory() is replaced by useNavigate() ;

import {useNavigate} from 'react-router-dom';
const navigate = useNavigate();
navigate('/home')