Introduction to ImmutableJS

As we discovered in Chapter 4: Redux, immutability is quite helpful when developing applications! It makes it so much easier to reason about what is happening to your data, as nothing can be mutated from somewhere entirely different.

The problem is that JavaScript is by default a mutable language. Other developers that don’t have this intricate knowledge of immutability might still mess up, mutate the state and break our app in unexpected ways.

Facebook released a second library called Immutable.js that adds immutable data structures to JavaScript! Let’s see what this looks like.