Framework: Use warn module in place of react/lib/warn

[aduth]

Related: #786, #776

This pull request seeks to replace existing usage of the react/lib/warn module with our own existing warn module. This is a prerequisite for upgrading to React 0.14. Facebook has moved library modules to a separate package, which they warn against using.

Note: If you are consuming the code here and you are not also a Facebook project, be prepared for a bad time. APIs may appear or disappear and we may not follow semver strictly, though we will do our best to. This library is being published with our use cases in mind and is not necessarily meant to be consumed by the broader public.

https://github.com/facebook/fbjs

Testing instructions:

Ensure that no references remain for react/lib/warn.

/cc @blowery 11943-gh-calypso-pre-oss

[blowery]

can config change over the life of the app? we could make warn a noop and then override it if we're not in prod

[aduth]

can config change over the life of the app? we could make warn a noop and then override it if we're not in prod

Sure, makes sense, and could shave a few cycles in production. What do you think about 726ccf7?

[blowery]

👍

[umurkontaci]

We can use also process.env.NODE_ENV !== 'production' and the block should be removed during compilation.

[aduth]

We can use also process.env.NODE_ENV !== 'production'

It's my understanding that we're not to use NODE_ENV and instead rely on the value specified in config, which is equal to the current environment's CALYPSO_ENV environment variable specified in the Dockerfile for each environment's build.

the block should be removed during compilation.

I'm not sure the uglifier is that smart. A common approach to achieve this is to use something like Webpack's DefinePlugin to replace occurrences of a text with false, which the uglifier would be smart enough to remove.

// 1. Variable comparison
var env = 'production';
if ( env !== 'production' ) {
    // Could be, but probably not removed by uglifier
}

// 2. Use `DefinePlugin` to replace `__DEV__` with `false`
if ( false ) {
    // Definitely removed by uglifier
}

[umurkontaci]

NODE_ENV is set in during the build process and will replaced by 'production' !== 'production', which will be removed by uglifier.

[lamosty]

@aduth What about using Envify. It could reduce this code process.env.NODE_ENV !== 'production' into (e.g.) 'production' !== 'production' and then

By running this through a good minifier (e.g. UglifyJS2), the above code would be stripped out completely.

[aduth]

@umurkontaci @lamosty - Indeed, I had overlooked that we're already specifying a DefinePlugin in our Webpack configuration to replace the NODE_ENV with the value from the current configuration. As you both suspected, this would be replaced by the uglifier. I jumped the gun here, but I can plan to open a separate pull request for the optimization.

[lamosty]

@aduth 👍

I'm sorry, I didn't notice that.