[acemarke]

Immutability is a common part of functional programming approaches. In Javascript, it's especially common in the React+Redux community. Redux expects you will update data immutably, and React works best when you do immutable updates as well.

Here's some good overviews of why and how to do immutable updates in JS:

https://redux.js.org/faq/immutable-data

https://redux.js.org/recipes/structuring-reducers/immutable-...

https://daveceddia.com/react-redux-immutability-guide/