This is a library providing the client-side editor component, with a bunch of modules (UI, collaboration), and a well-documented API through which to connect it

This is a library providing the client-side editor component, with a bunch of modules (UI, collaboration), and a well-documented API through which to connect it to surrounding code. It is written in ES6. The persistent data structures are not very involved, just objects that never get mutated after their initial construction.