Why

BRJS projects wanting to use NPM libraries can create a package.json file for their project containing the dependencies of any libraries they want, with a simple exporting script to ensure the libraries are actually available. There are a number of tools that can do the bundling.

How

Rollup isn't the fastest (WebPack is), and doesn't always produce the smallest bundles (for CommonJS, browserify does), but it has some advantages over Browserify, WebPack and SystemJS:

• It has a simple plugin system.
• Its bundles don't require ancillary libraries to work.
• For ES6 modules, it uses tree-shaking so that it only bundles the parts of a module you actually use.

At present however, there are two stumbling blocks I've hit:

1. I can't get any benefit from tree-shaking of NPM libraries because I can't enable the jsnext flag.
2. I can't have source-maps enabled because the CommonJS transformation plug-in doesn't support source-maps.