After burning a lot of time to get all the tooling I wanted working, for the umpteenth open source front-end javascript library I wanted to publish, I threw together this:

https://github.com/krakenjs/grumbler

Pretty opinionated on the tooling it uses, but good if you just want to say "Fuck it, I want to clone some boilerplate, write some code, and build/distribute it", then worry about the finer details later.