Private Route React Router Dom

private_route.js

import React, { useEffect } from 'react';
import { Route, useHistory } from 'react-router-dom';
import jwt from 'jsonwebtoken';
const PrivateRoute = ({ children, ...rest }) => {
  const history = useHistory();
  useEffect(() => {
    const onMount = async () => { // create an async function
      let localStorageUser = localStorage.getItem('user'); // check if user exists in localstorage 
      let isValid = true; // is the json web token still valid?
      if (localStorageUser) { 
        localStorageUser = JSON.parse(localStorageUser); // user was logged in so parse the stringified json
        const decodedJWT = await jwt.decode(localStorageUser.jwt);
        const dateNow = new Date(); // get the current date
        if (decodedJWT.exp < dateNow.getTime() / 1000) { // check if token expired
          isValid = false; // if expired its invalid
        }
      }
      if (!isValid) history.push('/login'); // if its not valid redirect to login
    };
    onMount(); // call function inside use effect hook
  }, []);

  return <Route {...rest}>{children}</Route>; // pass down any router props and render the children components
};

export default PrivateRoute;