Why do we need Express server when we have a backend ready already

Question

I am quite new to javascript and web application environment. I have seen a react web application project which had a public directory, a client directory and a server directory. I have few question

1. Why do we need an express server file setup in the frontend project if we already have backend APIs ready and backend server ready

2. Do we need an express server if we make the frontend on react and call the APIs to fetch the data for application.

3. Isn't the backend server and express server in the frontend project are same?

Answer 1

Why do we need an express server file setup in the frontend project if we already have backend APIs ready and backend server ready

You don't.

You need an HTTP server to listen for and respond to any Ajax requests you make from your client side code.

You need an HTTP server to listen for and respond to any requests for the HTML documents and static resources (JS, CSS, images, etc) that your pages need.

These can be the same HTTP server, different HTTP servers, written with Express or not written with Express.

React tutorials tend to ignore mentioning this and just dive in showing how to use Express for everything. Don't read too much into that.

Do we need an express server if we make the frontend on react and call the APIs to fetch the data for application.

No. See above.

Isn't the backend server and express server in the frontend project are same?

Maybe. It is up to you. See above.