Recs.
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Specs
Pros
Pro Well documented
The RequireJS module loader is extremely well documented. So no matter whether you're a pro at JS based web development or just a newbie, you will find the documentation very helpful whenever you're stuck or just starting out. Everything is well-defined and logically placed in proper sections in a manner such that it is very easy to understand.
Pro You don't need a server to get started
One of the best advantages of RequireJS over Browserify is that you don't need a nodejs environment to get started. Just "require" your dependencies and it takes care of loading them. By contrast, Browserify requires a running NodeJS implementation so you can build your one monolithic file, then you can push the file to your static web server.
Cons
Con Not the best solution for sharing client-side and server-side code
RequireJS is awesome for bundling and managing dependencies in an async manner. But the server-side needs neither of this killer features. Because of this it's not as good if your building a library that should work on both client and server (i.e. PouchDB).
Recommendations
Comments
Flagged Pros + Cons
Con No logical reason to use this if working in ES6
ES6 modules solve this problem in a more elegant, powerful and standards-based way.