title: How to include JavaScript libraries only in production build files of create-react-app?
body: <p>I'm trying to add a JavaScript library that is only included in the production build files generated by <a href="https://github.com/facebook/create-react-app" rel="nofollow noreferrer">create-react-app</a>.</p>
  
  <p>What's the best way to do this?</p>
  
  <p>Specifically, I'm trying to include the <a href="https://github.com/rollbar/rollbar.js" rel="nofollow noreferrer">Rollbar.js</a> client-side error monitoring library. I don't want it triggering every time I get an error in development/testing environments, so I only want it included in the files that are generated while running <code>npm run build</code>.</p>