An Appeal to All Package Managers
I have been thinking about it for a few months, and it seems like nothing exists out there. Every language out there has its own package manager, but everyone seems to be stuck with the same problem of frontend code. Obviously jQuery is used by virtually everyone. They can't support Composer, Bundler, npm, pip and god knows what. Building a package manager for JS/CSS could work, but the community is huge and scattered and getting broad adoption is going to be very difficult.
As far as I can see, and given the way Composer works, it would be fairly easy to build a central package repository - similar to Packagist - where people can submit package definitions for frontend libs. For instance I could go and add a twitter bootstrap package, define the URL where you can download it including some placeholder for the version. Then all we need is a list of version that's maintained. We could start by doing that by hand, or we can just point it to the git repo and it reads tags. That's how Packagist works - except that it reads the composer.json file in the git repo to get all the metadata that in this case would be entered manually.
If we do this, we then end up with a central repository of CSS and JS packages, and we can integrate it in Composer, so that Composer packages can depend on jQuery and it just works. That would be a good start, but the great thing would be to get everyone on board. And I don't mean everyone writing PHP. I mean everyone. The Ruby folks, the Python ones, Java, .NET, you name it. You all have package managers. All we have to do is agree on the API of the central package repository and on what metadata is needed. Then you can just add support for it in your package manager of choice, and we all benefit from the manual work put in to list packages. If it works, I'm sure some of the frontend packages will then add the metadata directly in their git/svn/.. repos so that we save on manual work. This would be a huge thing for everyone.
There are of course a few more details to settle regarding security and trust as well as exact package metadata, but I wanted to gauge the interest first, and then discuss further. I opened a frontend-packaging google group for that purpose, so if you are interested please join in. All it takes is a few open minded people and we could start one of the largest cross-language collaboration project ever. Sounds like fun!