Setup React Front-End in Existing Project

Let’s say you’re building with the MERN stack, for example. You have an existing project folder in which you’ve set up your entire backend server with Express and connecting your MongoDB database. Now you want to append a React frontend to the project. How do you setup a new React project within your existing overall project folder?

cd into your existing project folder and run this command:

npx create-react-app [your-folder-name]

This line basically creates a React application within a folder with whatever name you choose (ex. client) within your current project directory. npx is a tool that comes with Node.js that allows us to run create-react-app without having to install it globally on our machine.

To run your React project to make sure everything installed successfully, run these commands:

cd [your-folder-name]
yarn start

Run Frontend and Backend at the Same Time

We can run our frontend React app and backend Node.js server at the same time using the development tool concurrently.

Install concurrently as a development dependency:

npm i -D concurrently

Define the necessary scripts within your package.json:

"scripts": {
    "start": "node server",
    "server": "nodemon server",
    "client": "npm start --prefix client",
    "dev": "concurrently \"npm run server\" \"npm run client\""

The “dev” script uses concurrently to run the “server” and “client” scripts at the same time– with one single command.

In the root folder, run the “dev” script:

npm run dev

Installing Dependencies Within the React Project

You install dependencies within a submerged React project the same way you would within an non-submerged React project.

First, make sure you’re inside the React project folder. My folder name is client so:

cd client

Then, install dependencies with npm

npm i react-redux axios ...

Get Ride of Default Git Repository Within React App

Within the React app, a git repository is automatically initialized on the creation of the React app. If you already have a Git repository within your root project, you don’t necessarily need another one for your React project. If you wanted to delete the React repository, you would

  1. Delete the .gitignore and files within the React folder
  2. Delete the Git folder

This is the command to delete the git folder. Make sure you cd into your React folder before running this command or you might delete your root repository:

rm -rf .git

Node.js User Authentication with Bcrypt

In this lesson, we will be allowing users to create accounts, disguising their passwords to prevent hackers from stealing them, saving the accounts in a MongoDB database, and allowing users to log in with their account info.

In your project directory in Terminal, use this command to create a package.json file for your project

npm init -y

Any project that is using Node.js needs a package.json file. The file contains the project’s dependencies, source control information, and specific metadata.

Now install all the packages that our project will need using npm.

npm i express body-parser ejs mongoose bcrypt

I will show you how to set up the app.js file, but you’ll have to design the ejs (or html) and css files on your own.

In general, though, you’ll want to include something like this in your login & signup files:

<form action="/login" method="POST">
   <div class="form-group">
       <label for="email">Email</label>
       <input type="email" class="form-control" name="username">
   <div class="form-group">
        <label for="password">Password</label>
        <input type="password" class="form-control" name="password">
   <button type="submit" class="btn btn-dark">Login</button>

You will need a form that has an action parameter that posts to a route. You will take the user’s input using named input tags that can be referenced in the server file.

In your app.js file, require all the packages we installed earlier. Also create a saltRounds variable and set it to 10. We will use it later to salt our passwords.

const express = require("express");
const bodyParser = require("body-parser");
const ejs = require("ejs");
const mongoose = require("mongoose");
const bcrypt = require("bcrypt");
const saltRounds = 10;

More standard setup:

const app = express();

app.set('view engine', 'ejs');
  extended: true

mongoose.connect("mongodb://localhost:27017/authtestDB", {useNewUrlParser: true});

Create the User Model in MongoDB:

const userSchema = new mongoose.Schema ({
  email: String,
  password: String

const User = new mongoose.model("User", userSchema);

Set up the get routes so users can get to the different pages:

app.get("/", function(req, res){

app.get("/login", function(req, res){

app.get("/register", function(req, res){

Handle users entering their information into the login and register forms:

Posting to the Register Route

As you can see, we are using the bcrypt hash function. The function takes in the password given by the user in the request, the number of salt rounds (defined above), or times we want our password to be salted , and a callback function that can either return an error or the hashed (encrypted) password.

A new user based on our Mongo User Model is created using the username from the request and the encrypted password. Then, that user is saved into the MongoDB. If successful, the server will navigate the user to pages that require authentication."/register", function(req, res){
  bcrypt.hash(req.body.password, saltRounds, function(err, hash) {
    const newUser =  new User({
      email: req.body.username,
      password: hash
      if (err) {
      } else {

Posting to the Login Route

First, using the findOne function, we see if there are any emails in our database that match the one inputted by the user. This findOne function can return either an error or a found user/ matching user. If a user is found for the inputted email, bcrypt will proceed to compare the inputted password with the password for the email in the database. If it’s another match (result === true), the server will navigate the user to pages that require authentication."/login", function(req, res){
  const username = req.body.username;
  const password = req.body.password;

  User.findOne({email: username}, function(err, foundUser){
    if (err) {
    } else {
      if (foundUser) {, foundUser.password, function(err, result) {
          if (result === true) {