This repo demonstrates some React weirdness.

I was trying to implement a hook that allows me to do the following:

useOn()
  .who(window)
  .when('resize')
  .what(() => {
    console.log('resize!');
  });

Don't ask why. I just thought it was pretty.

Turns out you can, but using the approach I came up with, it only works in production.

Can you tell why?

Clone the repo, then:

npm i       # yarn
npm start   # yarn start

Then follow the instructions you see on the page, you will see my approach failing.

To see it running fine, you'll need to:

npm run start:prod   # yarn start:prod

Visit this repo's CodeSandbox, to see it failing (as you did if you ran it on your machine).

Visit this repo's Vercel deployment, to see it running fine.