Use dev-expression Babel plugin

[taion]

This drops the size of History.min.js from 27,016 B to 25,851 B.

[mjackson]

So we can already take advantage of this plugin without any code modifications? We're not currently using __DEV__ anywhere. What code is it removing?

[taion]

It's these two: https://github.com/4Catalyzer/babel-plugin-dev-expression#invariant, https://github.com/4Catalyzer/babel-plugin-dev-expression#warning

For a production build, this strips out calls to warning and removes the error messages for invariant.

Though https://github.com/rackt/history/blob/v1.13.0/package.json#L13 means that these will also happen for our un-minified UMD bundle, which I'm not sure if you want.

[taion]

And I have absolutely no idea why this isn't broadly used in the React ecosystem outside of Facebook's own modules. It's a free win for package size if you're using warning and invariant. You'd think the people who pulled out warning and invariant from fbjs would have noticed that there was this great Babel plugin that goes with them.

[agundermann]

👍 Thanks for this @taion . Finally a real solution for remix-run/react-router#556

[mjackson]

cc @BerkeleyTrue who maintains the warning package

[taion]

I think this is the last missing piece of the warning/invariant trinity - the Babel plugin that Facebook use to strip everything out for production builds. Not a massive space savings by any means, but it's "free", more or less.

[BerkeleyTrue]

Yes?