The basics of functional programming

Apart from following the best practices when we write JSX and use a linter to enforce consistency and find errors earlier, there is one more thing we can do to clean up our code: follow a Functional Programming (FP) style.

As discussed in Chapter 1, Everything You Should Know About React, React has a declarative programming approach that makes our code more readable.

Functional Programming  is a declarative paradigm, where side-effects are avoided and data is considered immutable to make the code easier to maintain and to reason about.

Don't consider the following section an exhaustive guide to functional programming; it is only an introduction to get started with some concepts that are commonly used in React and of which you should be aware.

First-class objects

In JavaScript, functions are first-class objects, which means that they can be assigned to variables and passed as parameters to other functions.

This allows us to introduce the concept...