token verification in react code example

Example: validate okta token ract

import * as React from 'react';
import { withRouter } from 'react-router-dom';
import { withAuth } from '@okta/okta-react';

export const AuthContext = React.createContext();

const getUserFromToken = token => {
  if (token) {
    try {
      return JSON.parse(atob(token.split('.')[1]));
    } catch (error) {
      // ignore
    }
  }

  return null;
};

export const AuthProvider = ({ children }) => {
  const [state, setState] = React.useReducer((oldState, newState) => newState, {
    loading: true,
    token: undefined,
    user: null,
  });

  const updateAuth = async auth => {
    const token = (await auth.getIdToken()) || null;
    if (token !== state.token) {
      setState({
        token,
        loading: false,
        user: getUserFromToken(token),
      });
    }
  };

  return (
    <AuthContext.Provider value={{ ...state, updateAuth }}>
      {children}
    </AuthContext.Provider>
  );
};

export const AuthHandler = withAuth(
  withRouter(({ auth, location }) => {
    const { updateAuth } = React.useContext(AuthContext);

    React.useEffect(() => {
      updateAuth(auth);
    });

    React.useEffect(() => {
      if (location.pathname === '/login') auth.login('/');
      if (location.pathname === '/logout') auth.logout('/');
    }, [auth, location.pathname]);

    return null;
  }),
);