When developing APIs or writing integration solutions, we often fetch data from multiple sources and combine them together. This requires quite a bit of boilerplate even if you use utility libraries like lodash.

This library aims to be provide a simple type-safe utility that makes the task of combining multiple collections simpler using an intuitive association API.

You may find this API to be reminiscent of association APIs found in ORMs. However, collection-joiner is completely agnostic about how these collections are obtained - so you could for example, fetch a list of users from a database, a list of departments from another service, a list of roles from a key value store and merge them into a single hierarchy when constructing a response.