Динамическая подгрузка js, css в REACT?

import React from 'react'
import ReactDOM from 'react-dom'
import { Router, Route, Switch } from 'react-router'
import createHistory from 'history/createBrowserHistory'

// SHARED
import './shared/stylesheets/base.scss'

// APPS
import Welcome from './welcome'
import Authorization from './authorization'
import Registration from './registration'

const history = createHistory()
const div = document.createElement('div')
document.body.append(div)

ReactDOM.render(
  <Router history={history}>
    <Switch>
      <Route component={Welcome} exact={true} path="/" />
      <Route component={Authorization} exact={true} path="/sign_in" />
      <Route component={Registration} exact={true} path="/sign_up" />
    </Switch>
  </Router>,
  div
)