Check self.process before reading for browser compatibility

[keanulee]

With this patch, browsers can directly run the ES module build of Redux from https://unpkg.com/redux@4.0.0-beta.2/es/redux.js?module and other tools that converts package names to paths.

Fixes #2907

[timdorr]

Thanks for this. I think it looks good, but anyone else want to chime in?

[jimbolla]

@timdorr The thing to verify is that those blocks still get removed in the prod build. I suppose comparing the prod build size before and after this change would work.

[timdorr]

Yep, I'll want to verify locally to be sure. I'll try to run that through tonight or tomorrow at some point.

[kaushik94]

@jimbolla @timdorr the way react does this check is by defining a __DEV__ variable. Chances are you already knew this. Although I don't know how to define this globally, we can still define something like this in index.js file and export from there to check if(__DEV__) , I think this would be a cleaner solution? I would be glad to implement this, and also would like to work on this library for self-improvement. I would be happy if I can contribute, even if it's a small change :)

[timdorr]

@kaushik94 That's transformed into a NODE_ENV check during the build process. They use it as a shorthand while coding, but it's not how the build comes out compiled.

[timdorr]

I checked against the production build, and they are still sticking around in the UMD build, unfortunately. I'm not sure there is a good way to fix this internally at the moment.

I would instead either use the UMD version or "polyfill" with window.process = { env: 'production' } before importing.