Mastering Immutable.js

Chaining method calls

Immutable data doesn't just sit inside of a constant. Somehow, your applications need to make use of this data. These are called side-effects. A side-effect is something that is effected by immutable data, such as rendering data on the screen in a user interface or writing data to a file. By contrast, operations performed on immutable collections are either persistent changes or sequence transformations, both of which result in new collections. These operations don't have any side-effects; they just result in new data being created. Another term used for functions that don't cause side-effects is pure functions.

With Immutable.js, you start with a collection of immutable data and work your way toward some sort of side-effect. ...