How to Create a React Frontend, Express Backend, and Connect Them Together

Some may feel a bit of confusion when talking about frontend and backend. Here, we will discuss the steps for building a frontend using React, a backend using Express.js, and connect them together.

The popularity of JavaScript is increasing day by day. If we learned JavaScript, we can develop both backend and frontend with it. This makes things easier for a full-stack developer.


Here in this article, we are simply creating an Express backend, a React frontend and connect them together. To follow this article, you must have basic knowledge in JavaScript, React, and Express.

I also assume that you are aware of the terms backend, frontend etc.

What we will learn

After completing this article, we will learn,

  1. What is Express?
  2. What is React?
  3. To create an Express backend
  4. Create a react frontend
  5. We will fetch the data from the backend and show it in our React app.

If you are a beginner in React, it’s recommended that you’d start with creating a basic counter app, to-do list application, or an attendance management app that’ll help you get started with React concepts.

Note that, we are only dealing with JSON data in the express backend and connect it to React frontend. If you want to connect a database with the backend, refer to the article, connect MongoDB Atlas With Express Backend.

What is Express?

Express is a popular unopinionated web framework, written in JavaScript and hosted within the Node.js runtime environment. It is also a modern backend technology and popular among new developers.

Other than Express, there is a list of frameworks which helps us in backend development. I have listed some of them below.

What is React?

React, a simple and powerful library is gaining huge popularity among developers nowadays. The component architecture is making react an easier way of making the complicated web application UIs in record time. Also, the maintenance and bug fixes are simpler because the codes are divided into components.

Because of browser support javascript, there is a huge list of front-end JavaScript development frameworks/libraries. But the popular among them are listed below.

Here we are choosing Express as our backend technology and React as our front-end technology to build a sample application.

Creating a Node/Express Backend

First, we need to create a Backend to take requests from frontend and send responses according to it.

To get an idea about the express project we are going to build, I have shown the complete file structure of our project below.

1. Install Nodejs

Node.js actually provides a runtime environment to execute JavaScript code from outside a browser. NPM, the default package manager for Nodejs is used for managing and sharing the packages for any JavaScript projects.

Node.js and NPM are used by Express for the management of dependencies and runtime.

Installing Nodejs on our system may differ with our Operating System.

For Windows users, I have already written an article install Node.Js And NPM On Windows 10.

For macOS, use the below link to download and install Nodejs.

Ubuntu users can install Node by executing below commands.

curl -sL | sudo -E bash -
sudo apt-get install -y nodejs

Others follow the below URL for installation steps.

2. Install Nodemon

Nodemon is a tool that helps develop node-based applications by enabling the live reloading feature. Starting our Express app with Nodemon will reload the apps if there is a change in the code.

So install the Nodemon tool globally on our system.

npm i -g nodemon

3. Create a Project Directory

Create a project directory and navigate to it using our Command Prompt/Terminal. This can also be done using the Graphical User Interface(GUI).

mkdir express-backend
cd express-backend

4. Initialize a Node.js Project

It requires a package.json file inside our project directory to work with Node.js projects. So we need to initialize a Node.js project using the below command.

npm init

5. Install Express

In this project, we are going to make REST APIs using Express.js framework. So we need to install Express for our project.

npm i express --save

6. Install Cors

CORS is a node.js package for providing a Connect/Express middleware that can be used to enable CORS with various options.

npm i cors --save

7. Install Body-Parser

To handle HTTP POST request in Express.js version 4 and above, we need to install the middleware module called body-parser. When we don’t use it, we get the raw request, and your body and headers are not in the root object of the request parameter.

npm i body-parser --save

8. Install Morgan

Morgan is basically a logger, on any requests being made, it generates logs automatically.

npm i morgan --save

So after creating and installing 4 packages, the package.json file looks like the below.

9. Configure the Root File (index.js)

When initializing NPM, we selected index.js as our entry point(root file). So the app directs to index.js first and so we need to create and configure it.

9.1 Create index.js

We can create a file named index.js in our project directory using GUI or using our terminal.

touch index.js

9.2 Import all packages installed

Import all the packages we have installed earlier to our index.js file.

const express = require("express");
const app = express();
const cors = require("cors");
const bodyParser = require("body-parser");
const logger = require("morgan");

9.3 Define port number

Now define a port number in which our app needs to be started.

const port = process.env.PORT || 3001;

9.4 Use Logger

Use the logger package we have imported to get the log details of our application if needed.


9.5 Use Cors

Now use cors to enable Cross-Origin Resource Sharing.


9.6 Use Body-Parser

Also, use body-parser to handle HTTP POST requests.

app.use(bodyParser.urlencoded({ extended: true }));

9.7 Import and use players route

Yes. We did not create any route yet. But in the future steps, it will be made and configure. So just add the below lines in our root file.

const playersRouter = require("./routes/players");
app.use("/players", playersRouter);

9.8 Listen to the port we defined

We already defined a port number and it needs to be used when starting our project. So this port number must listen to our application.

app.listen(port, function() {
  console.log("Runnning on " + port);

9.9 Export the app module.

Now export the module app we have created.

module.exports = app;

10. Create a dummy database

Some data needs to sent to the frontend with a GET request. So it needs to create a dummy database. So first create a file named dummyDatabase.js, feed some data and export it.

touch dummyDatabase.js

The above command will generate a file named dummyDatabase.js. Open it and paste the array of objects players in it and export it.

let players = [
  { _id: 1, name: "Sachin", runs: "18426" },
  { _id: 2, name: "Dhoni", runs: "10500" },
  { _id: 3, name: "Virat", runs: "10843" }
module.exports = players;

11. Create Routes

Now we can create routes to handle the requests from the front-end. In this project, we are only dealing with getting the list of players and getting single-player details. So we need two routes.

11.1 Create players.js route

We need to create a route file where all the functions of players are defined. So create a players.js file inside a directory named routes.

mkdir routes
cd routes
touch players.js

11.1 Define router

Import express package and put express.Router() in a variable called router.

const express = require("express");
const router = express.Router();

11.2 Import dummy database

Now import the dummy database file we have created earlier.

let players = require("../dummyDatabase");

11.3 Create a route to get the complete list of players

We want to get the complete list of players in our database. So we need to create a router for GET request to /list.

router.get("/list", async (req, res) => {
  try {
      data: players
  } catch (err) {
      message: "Some error occured",

Now, if we run our project, the below link will return the complete list of players.


11.4 Create a route to get a single-player details

We got the full player list. Now we need each player details. This can be done by passing the id of each player as the API parameter from the frontend.

:id is the player_id passed as the URL parameter. It is used to find a single-player with the _id.


The id that we are passing from frontend can be accessed from here as and it needs to convert to the number type before comparing with database _id because the _ids in the database are in the form of numbers.

router.get("/list/:id", async (req, res) => {
  let { id } = req.params;
  id = Number(id);
  try {
    let player = players.find(player => player._id === id);
      data: player
  } catch (err) {
      message: "Some error occured",

So, the below link returns the details of player 3.


11.5 Export the module

Now export the router module we have created.

module.exports = router;

So the complete players.js file will look like below.

12. Running our Backend

So we have created a RESTful API using Nodejs and Express. Now we can run our backend using Nodemon. Nodemon can watch the changes we are adding to our project and update the live server itself.

nodemon index.js

13. Testing the APIs

So our server is running on port 3001. The recommended method of testing our APIs is with Postman and it can be downloaded using the link below.

But here, our backend only dealing with getting requests without headers. So we can simply test it within our browser.

13.1 GET the complete list of players

The API URL below will show the complete list of players as JSON.


This will return the data of players from our Express backend without a specific format. I am using the JSON Formatter extension in my chrome browser to format the JSON data.

13.2 GET a single-player details

To get the details of a single player, we need to pass the id with our API URL. So the below URL will return the single-player( _id: 2) details.


Creating a React Application(Frontend)

So our Express backend is ready and now we can create a React frontend application to connect with this backend.

To get an idea about the React project we are going to build, I have shown the complete file structure of our project below.

1. Install and Set Up React

We have already installed Nodejs on our system. So we can create a React application using NPX easily.

npx create-react-app react-frontend

If it hit with any errors, refer the detailed guides.

After creating a React application, open the project using a code editor. I recommend the VS code for this.

2. Adding Bootstrap(optional)

This is an optional step for styling our React application by adding Bootstrap CDN to the index.html file inside /public directory.

Under index.html file, add the below lines between <header></header> section.

<link rel="stylesheet" href=""/>

So the complete index.html file will look like as below.

3. Configure App.js

Now our working area is App.js under /src directory. First of all, Clear all the contents in App.js first. We can start coding from line 0 onwards.

3.1 Import React and Component

At first, we need to import React and Component from react package.

import React, { Component } from "react";

3.2 Create a class App and export it

We need to create a class named App and export it. We are going to code everything inside this class. Because our react app is small, it does not need to divide our project as components.

export default class App extends Component {


3.3 Initialize all the states inside the constructor

So we need states to store data. We need to initialise the below states.

  • list: if the state list is true, the list of players component will be displayed.
  • card: if the state card is true, the single-player card will be displayed.
  • players: this state stores the list array of players from the backend.
  • player: this stores a single-player detail from the backend.
constructor(props) {
    this.state = {
      list: true,
      card: false,
      players: [],
      player: {}

3.4 Fetch the list of players from API and store it in the state

Now we need to fetch the list of players from the API we have created using Express earlier. This data needs to be stored in the state players. These operations must be done before mounting the component. So fetch the players list and store it inside a state before component mounts. So this has to be done inside componentDidMound().

componentDidMount() {
  .then(response => response.json())
  .then( responseJson=> {
    this.setState({ });

3.5 Create a function to handle the view of a single-player card

Now we need to create a function showCard() which handles the view of a single-player detail card. Inside this, it needs to fetch each player detail with the id and store it in a state named player.

This function can also be used for UI functions. Here we make list value false and card value true. This will hide players list view and show single-player card view.


We can also implement this feature using React Navigation, but I not willing to complicate this small project.

showCard=id=> {
  .then(response => response.json())
  responseJson=> {this.setState({ })},

3.6 Create a function to handle the view of the player’s list

We have a Back button in card view and pressing it will call a function named showList() where it makes card value false and list value true. This will show players list view and hide the single-player card view.

showList = () => {
     card: false,
     list: true

3.7 Start Render function and return the view

Now we can start the render() function and return our views.

<div className ="container">


This will show up a blank page in our browser window if the project is started.

So, before starting our react application, we need to add two UI components. The list view and the card view.

3.8 Set up the list view to show players list

Show this list view only if the state list if true. In this situation, map through the array stored in the state players and show each player name inside the map function. Also, when clicking each name, there have to execute the function showCard(). We have to pass the player id with this function because the data needs to be fetched from backed and shown in the card.

        {this.state.list ? (
          <div className="list-group">
            { => (
                onClick={() => this.showCard(player._id)}
                className="list-group-item list-group-item-action"
        ) : null}

3.9 Set up the card view to show a player detail

Show this card view only if the state card is true. In this situation, show details in the player state.

        {this.state.card ? (
          <div class="card" style={{ width: "18rem" }}>
            <div class="card-body">
              <h5 class="card-title">{}</h5>
              <p class="card-text">{this.state.player.runs}</p>
              <div onClick={() => this.showList()} class="btn btn-primary">
        ) : null}

So the complete App.js file will look like below.

4. Running our Frontend

We created a React frontend successfully and now it can be started using the following command.

npm start

This opens up our application in port 3000 and can be accessed with the below URL.



The complete project here I made is uploaded in GitHub for reference.




So, here we discussed the steps for creating a React frontend, an Express backend and connect them together. We also added the GitHub repositories of both projects in this article.

4 thoughts on “How to Create a React Frontend, Express Backend, and Connect Them Together

  1. With zero knowledge about Express and React, I was browsing the internet to do a sample application. In most of the blogs, they configured both in the same application. I couldn’t keep my application with both Express and React running together. I didn’t even understand that one is used as a server-side component and the other is the client technology. Your blog came to rescue. I could understand a lot from your other blogs too. Just want to let you know how much it was helpful.

  2. I could run it locally on Windows but not on an Ubuntu server
    The first error is “Invalid Header” for development server xxx:3000
    And the next error after moving to the production server
    npm run build
    npm install -g serve
    serve -s build
    is App.js:15 GET http://localhost:3001/players/list net::ERR_CONNECTION_REFUSED
    What should I configure on Ubuntu so that Front End can access Back End ?
    I can access the Back end from the command line using curl
    root@:~# curl -X GET http://localhost:3001/players/list

    It is the front end that can not access – what configuration or security should I enable for the 2 servers to see each others on the same machine ?

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