Hipmunk frontend code is mainly written using CoffeScript. We are using the Webpack loader to transpile it to JavaScript. This process is quick, except when the Webpack watcher is lunched for the first time.

The luncher code is small and straightforward. It is basically a bridge between Webpack and the official npm module.

Each time Webpack need to recompile a CoffeeScript file, it calls the loader, passing directly the full source code. The loader is simply transpiling the source into JavaScript and returns it to Webpack.

While in watch mode, the transpilation is extremely quick: Webpack recompile only the file that got modified. But lunching Webpack can take a very long time as it is recompiling everything from scratch.

Webpack watching...
Compilation starting at: 19:10:31
Hash: 063a8e90a05b83f43d51
Time: 27427ms

After a fork of the loader and the addition of a file cache, it became much faster.

Webpack watching...
Compilation starting at: 19:11:31
Hash: 063a8e90a05b83f43d51
Time: 17760ms

10 sec. less. Not too bad. The bigger the code base is, the bigger this is saving. This will also speed up the testing/CI infrastructure of Hipmunk as we regenerate the JavaScript for every build.

The next step is to send a pull request with this change. Not sure how it will goes, considering that I used sync file I/O for everything :p