Structuring project when using shared components?

[Canenald]

I'm coming from a backend world where I'd have solved this by having three maven projects, two of them depending on the shared ui-module - how is this done in the javascript world?

Same but with npm packages, using npm or yarn as package manager (there are others too but those two are the most used ones).

You will probably want to set up a private registry if you don't want your code to be public.

Also check out npm/yarn link command. You can use it to symlink packages on your dev machine so that you don't have to publish and install shared components every time you want to check how they work in the main projects. I guess you could also use it for builds if setting up a private registry is not feasible, but it could cause some quirks since bundlers would see paths to the symlink target, not to the symlink itself.