Authentication is an important part of any app, and doing authentication on a single-page app adds some complexities of its own.

 Authentication flow

This is a basic diagram of our Authentication flow. We'll dive deeper into each portion in the sections below.

 Authentication App

We can implement an authentication layer in a small React application.

We can mainly split this into two parts: 

1. ‘Creating Components’. In this part, we will install dependencies for our project and create a basic application server and essential React components. We will add handlers for AJAX requests on a server side and validate them.
2. ‘JSON Web Token’. In this part, we will focus on a user registration using an email address. For authentication, we will use JSON Web Token (JWT). 

There is a simple tutorial i followed to do Authentication in React.

You can also fellow this and build a simple authentication in your apps.

Authentication in React Applications

1.  Part 1: Creating Components

2. Part 2: JSON Web Token