improve initial build times using happypack

[amireh]

Enables parallel loader application for jsx, json, sass, and less
sources using five background threads.

Some env notes:

• you can disable HappyPack entirely by setting HAPPY=0 in your env
• you can disable HappyPack's caching by setting HAPPY_CACHE=0
• you can make HappyPack more verbose by setting HAPPY_VERBOSE=1 (useful
  to see the state of cache)
• HappyPack's state and cache can be reset by rm -r .happypack/

Other minor changes:

• made those loaders only apply to files under /src (a whitelist)

[amireh]

I would also suggest using eval as a devtool instead of inline-source-map as the former is much faster and works just fine for development purposes.

[igoldny]

looks good, json files broken tho.
try to import json file in your code you will get an error.

[mmahalwy]

Happypack is awesome! My only concern is sourcemaps.

[amireh]

@igoldny will take a look, created a ticket for it: amireh/happypack#30

@mmahalwy I've a ticket (amireh/happypack#28) open for source-map support, just need to find some time to tackle it.

[oyeanuj]

@amireh does this PR need to be updated given that source-map support is there now?

[amireh]

@oyeanuj Yes, just did the upgrade and re-tested.

I also went over the reported json-loader issue and was not able to reproduce, there's now an example/test for json-loader and it seems to function correctly.

[oyeanuj]

@amireh Thanks for the update. I was trying it out and the only issue I ran into was when I was trying to expand it to include css (instead of sass). Following exactly how 'sass' loader was configured, I got the following errors.

Any thoughts on this? Let me know if I should move this conversation to the happypack repo instead?

assert.js:90
[0]   throw new assert.AssertionError({
[0]   ^
[0] AssertionError: HappyPlugin[css]; you have not specified any loaders and there is no matching loader entry with this id either.

In module.exports:

createSourceLoader({
    happy: { id: 'sass' },
    test: /\.scss$/,
    loader: 'style!css?modules&importLoaders=2&sourceMap&localIdentName=[local]___[hash:base64:5]!autoprefixer?browsers=last 2 version!sass?outputStyle=expanded&sourceMap',
    }),
createSourceLoader({
    happy: { id: 'css '},
    test: /\.css$/,
    loader: 'style!css?importLoaders=2&sourceMap&localIdentName=[local]___[hash:base64:5]'
}),

In plugins array:

createHappyPlugin('sass'),
createHappyPlugin('css')

[oyeanuj]

Actually, ignore my question above. Once I changed devtool to eval, it started working. Oh well~!

[ali]

Looks like this one was completely removed?

[bertho-zero]

No woff and woff2 are replaced by the woff2? regex

[ali]

ah, I missed that! :)