How one can Construct a Easy React app With Categorical API

Have you ever ever wished to construct React app with Categorical API? This tutorial will present you ways. You’ll learn to create a easy React app and tips on how to fetch information from totally different API endpoints. Then, you’ll learn to construct API with Categorical.js, tips on how to create controllers and routes and tips on how to implement them.


The objective of this tutorial is to indicate you tips on how to construct React app with Categorical. To be extra particular, you’ll be taught three issues. The very first thing is tips on how to create React app. The second factor is tips on how to create Categorical API. The third factor is tips on how to join the React app with Categorical API.

Undertaking construction

To maintain every part tidy we’ll maintain the entire app in a single listing. This listing will include three folders: public for static information, server for specific server and src for React app. The server listing may even include three folders: controllers for API controllers, routes for API endpoints and information for mock information.

Apart to those folders there shall be server.js file. This file will include the configuration in your specific server. The src listing will include two folders: parts for React parts and css for kinds. On the foundation stage, there shall be primary file in your React app, the index.js.

For those who use TypeScript in supply folder may even be react-app-env.d.ts for TypeScript definitions and tsconfig.json. A minimum of in the event you resolve to generate your React app utilizing create-react-app and TypeScript template. The final file in root listing shall be buildScript.js. This file accommodates script for constructing the React app and transferring it to server listing.

├─ node_modules
├─ public
│ ├─ favicon.ico
│ ├─ index.html
│ ├─ logo192.png
│ ├─ logo512.png
│ ├─ manifest.json
│ └─ robots.txt
├─ server
│ ├─ controllers
│ │ ├─ home-controller.js
│ │ └─ users-controller.js
│ ├─ information
│ │ └─ customers.json
│ ├─ routes
│ │ ├─ home-route.js
│ │ └─ users-route.js
│ └─ server.js
├─ src
│ ├─ parts
│ │ └─ app.tsx
│ ├─ css
│ │ └─ index.css
│ ├─ index.tsx
│ ├─ interfaces.ts
│ ├─ react-app-env.d.ts
│ └─ serviceWorker.ts
├─ .env.development
├─ buildScript.js
├─ package deal.json
└─ tsconfig.json

Be aware: For those who don’t need the browser to robotically open each time you begin your app there’s a method to cease this. Create .env.development file within the root listing of your app, the place is package deal.json. Inside this file write add BROWSER=none.

Creating React app

Let’s begin with the front-end half, the React app as first. The quickest means to do that is through the use of create-react-app. Utilizing this boilerplate may be very simple. For those who use npm you need to use npm init react-app react-express-app --typescript. Another choice is utilizing npx. It will can help you use the boilerplate with out putting in it.

To make use of npx use npx create-react-app react-express-app --typescript command. For those who use yarn use yarn create react-app react-express-app --typescript. I shall be utilizing TypeScript, a superset of JavaScript. Nevertheless, you don’t have to make use of it in the event you don’t need. For those who don’t wish to use it, omit the --typescript flag on the finish of chosen command.

App part

For the aim of this tutorial, we’ll do the work largely in only one part, the App. Inside it, we’ll use useState to retailer brief welcome message and array with customers. We are going to fetch each these info from our specific API. For fetching the info we’ll use native fetch API.

When the parts mounts, we’ll all the time fetch the welcome message. To do that, we’ll create fetchApi operate. Subsequent, we’ll use useEffect() react hook and name fetchApi() from there. To make sure this hook will hearth solely as soon as, on preliminary render, we’ll move [] into the useEffect() hook because the second argument.

In contrast to fetching the welcome message fetching customers won’t be automated. As an alternative, we’ll create fetchUsers() operate and add is as onClick handler on a button. So, once you click on the button, app will fetch particular endpoint for customers and replace app state. It will mount easy desk part itemizing all customers and their information.

// src/parts/app.tsx

// Import vital dependencies
import React, { useEffect, useState } from 'react'

// Create interface for person object (TypeScript solely)
interface UserUI {
  id: string;
  username: string;
  title: string;
  electronic mail: string;

// Create App part
operate App() {
  // Put together state hook for welcome message
  const [welcomeMessage, setWelcomeMessage] = useState('')

  // Put together state hook for customers listing
  // Be aware: <UserUI[]> is for TypeScript
  // It specifies the form of usersList state
  const [usersList, setUsersList] = useState<UserUI[]>([])

  // Create async operate for fetching welcome message
  const fetchMessage = async () => {
    // Use Fetch API to fetch '/api' endpoint
    const message = await fetch('/api')
      .then(res => res.textual content()) // course of incoming information

    // Replace welcomeMessage state

  // Use useEffect to name fetchMessage() on preliminary render
  useEffect(() => {
  }, [])

  // Create async operate for fetching customers listing
  const fetchUsers = async () => {
    const customers = await fetch('/customers/all')
      .then(res => res.json()) // Course of the incoming information

    // Replace usersList state

  return (
    <div className="app">
      <header className="app-header">
        {/* Show welcome message */}

        {/* Button to fetch customers information */}
        <button onClick={fetchUsers}>Fetch customers</button>

        {/* Show desk of customers after fetching customers information */}
        {usersList.size > 0 && <desk>

            { UserUI) => (
              <tr key={}>
                <td>{person.electronic mail}</td>

export default App

Be aware that the fetchMessage() makes use of textual content() to course of information from API whereas the fetchUsers() makes use of json(). That is on objective. The “/api” endpoint, we’re going to create, returns a easy textual content. The “/customers/all” returns a json. Ensure to make use of right technique. In any other case, you’ll run into points.


The index.tsx will keep just about the identical because the default created by create-react-app boilerplate.

// src/index.tsx

// Import vital dependencies
import React from 'react'
import ReactDOM from 'react-dom'

// Import App part
import App from './parts/app'

// Import kinds
import './css/index.css'

// Import service staff
import * as serviceWorker from './serviceWorker'

// Render App part within the DOM
    <App />
  , doc.getElementById('root')

// If you need your app to work offline and cargo sooner, you'll be able to change
// unregister() to register() under. Be aware this comes with some pitfalls.
// Study extra about service staff:


In case of kinds, we’ll add some basic kinds and resets resembling correct box-sizing, no margin on physique, font settings and a few kinds for customers desk. Aside from that, be happy so as to add your individual CSS kinds to vary how the React apps seems like.

/* src/css/index.css */

/* Common kinds & resets */
*::earlier than,
*::after {
  box-sizing: border-box;

html {
  font-size: 16px;

physique {
  margin: 0;
  font: 1rem -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;

/* Format kinds */
.app {
  text-align: middle;

.app-header {
  min-height: 100vh;
  show: flex;
  flex-direction: column;
  align-items: middle;
  justify-content: middle;
  font-size: calc(10px + 2vmin);
  coloration: #222;

/* Desk kinds */
desk th,
desk td {
  padding: 8px;
  font-size: 16px;
  text-align: left;

Updating mission workflow

The front-end a part of our React app is prepared. Now, earlier than we begin engaged on the API, the specific sever, we have to make some updates to our workflow. We have to add some new dependencies and scripts.

Including dependencies

The very first thing we’ll want is so as to add new dependencies vital for specific API. Crucial dependency is specific. Then, we may even add some middleware. Middleware are features that show you how to execute some very helpful duties in an easy means. For instance, they may also help you parse request our bodies, add response headers, compress HTTP responses, allow CORS, HTTPS and extra.

The middleware we’ll add, and use, shall be body-parser (parses HTTP request physique), compression (compresses HTTP responses), cookie-parser (parses cookie header and populates req.cookies), cors (permits CORS) and helmet (permits HTTPS). Check out express docs for the total listing of obtainable middleware.

npm i specific body-parser compression cookie-parser cors helmet

# or
yarn add specific body-parser compression cookie-parser cors helmet

Apart to those we may even add some extra helpful dependencies. These are concurrently, cross-env and nodemon. The concurrently will assist us run a number of npm scripts directly. That is helpful if you wish to run your React app and specific API directly in a single terminal window.

The cross-env makes it simpler to set, and use, Node atmosphere variables that work on all platforms. Lastly, the nodemon. This dependency will make it simpler to develop the specific server as a result of it may look ahead to modifications in particular information or directories.

So, once you change one thing, you don’t should restart the server. nodemon will robotically refresh/restart the server so you’ll be able to proceed working.

npm i -S concurrently cross-env nodemon

# or
yarn add -D concurrently cross-env nodemon
// /package deal.json
// ...
"dependencies": {
  "body-parser": "1.19.0",
  "compression": "^1.7.4",
  "cookie-parser": "^1.4.5",
  "cors": "2.8.5",
  "specific": "4.17.1",
  "helmet": "^3.22.0",
  "react": "16.13.1",
  "react-dom": "16.13.1"
"devDependencies": {
  "@testing-library/jest-dom": "4.2.4",
  "@testing-library/react": "9.4.0",
  "@testing-library/user-event": "7.2.1",
  "@sorts/jest": "24.9.1",
  "@sorts/node": "13.9.5",
  "@sorts/react": "16.9.26",
  "@sorts/react-dom": "16.9.5",
  "concurrently": "5.1.0",
  "cross-env": "^7.0.2",
  "nodemon": "2.0.2",
  "react-scripts": "3.4.1",
  "typescript": "~3.8.3"
// ...

Including npm scripts

At this second, your package deal.json accommodates solely scripts for working, constructing, testing and ejecting the React app. We additionally want so as to add scripts for working specific server, working each, the server and likewise the app in parallel and likewise for constructing the app.

First we’ll rename present script for working React app, the begin, to start-front. The script for constructing, the construct, to build-front. Subsequent, we’ll add script for working the specific server, start-server. This script will use cross-env to set Node atmosphere variable and nodemon to run, and watch, the server.

Foremost job for constructing the app shall be construct. It will use Node to execute scripts in buildScript.js.

// /package deal.json
// ...
"scripts": {
  "construct": "node ./buildScript",
  "start-server": "cross-env NODE_ENV=development nodemon server/server.js --watch server/*",
  "start-front": "react-scripts begin",
  "build-front": "react-scripts construct",
  "eject": "react-scripts eject",
  "take a look at": "react-scripts take a look at",
  "begin": "concurrently "npm run start-server" "npm run start-front" --kill-others"
// ...

Setting proxy

There’s yet one more factor to do. We have to add proxy. It will enable us to redirect any requests, resembling fetching information, to our API to particular host and port. The necessary factor right here is to make use of the identical host and port your specific is working on. On this tutorial we’ll run our specific app on http://localhost:4000.

We have to use the identical host and port and set it as proxy in package deal.json. Now, after we attempt to fetch /customers/all app will robotically fetch http://localhost:4000/customers/all.

// ...
"proxy": "http://localhost:4000"
// ...

The entire package deal.json seems like this:

// /package deal.json

  "title": "react-express-app",
  "model": "1.0.0",
  "personal": true,
  "eslintConfig": {
    "extends": "react-app"
  "browserslist": {
    "manufacturing": [
      "not dead",
      "not op_mini all"
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
  "proxy": "http://localhost:4000",
  "scripts": {
    "construct": "node ./buildScript",
    "start-server": "cross-env NODE_ENV=development nodemon server/server.js --watch server/*",
    "start-front": "react-scripts begin",
    "build-front": "react-scripts construct",
    "eject": "react-scripts eject",
    "take a look at": "react-scripts take a look at",
    "begin": "concurrently "npm run start-server" "npm run start-front" --kill-others"
  "dependencies": {
    "body-parser": "1.19.0",
    "compression": "^1.7.4",
    "cookie-parser": "^1.4.5",
    "cors": "2.8.5",
    "specific": "4.17.1",
    "helmet": "^3.22.0",
    "react": "16.13.1",
    "react-dom": "16.13.1"
  "devDependencies": {
    "@testing-library/jest-dom": "4.2.4",
    "@testing-library/react": "9.4.0",
    "@testing-library/user-event": "7.2.1",
    "@sorts/jest": "24.9.1",
    "@sorts/node": "13.9.5",
    "@sorts/react": "16.9.26",
    "@sorts/react-dom": "16.9.5",
    "concurrently": "5.1.0",
    "cross-env": "^7.0.2",
    "nodemon": "2.0.2",
    "react-scripts": "3.4.1",
    "typescript": "~3.8.3"

Creating construct script

I briefly talked about that we are going to use customs script to construct the React app. We are going to use this script in npm construct script. Put merely, what this script does is it runs react-scripts construct after which copies the entire construct of the React app to “./server/construct” listing.

// /buildScript.js

const fs = require('fs')
const fse = require('fs-extra')
const childProcess = require('child_process')

if (fs.existsSync('./construct')) {

// Run 'react-scripts construct' script
childProcess.execSync('react-scripts construct', { stdio: 'inherit' })

// Transfer app construct to server/construct listing
fse.moveSync('./construct', './server/construct', { overwrite: true })

Constructing Categorical backend

Okay. React app is prepared and dependencies and scripts are prepared as nicely. It’s time to create our easy specific sever. Let’s get began.

Including mock information

As you keep in mind, the app accommodates operate to fetch listing of customers. We have to get these information from someplace. For the sake of simplicity, we’ll create a brief json, in information listing, containing information of couple of customers. When the React app fetch the /customers/all endpoint, our specific app will ship this json as a response.

// server/information/customers.json
    "id": "u0001",
    "name": "Leanne Graham",
    "username": "bret",
    "email": "[email protected]"
    "id": "u0002",
    "name": "Ervin Howell",
    "username": "antonette",
    "email": "[email protected]"
    "id": "u0003",
    "name": "Clementine Bauch",
    "username": "samantha",
    "email": "[email protected]"
    "id": "u0004",
    "name": "Patricia Lebsack",
    "username": "karianne",
    "email": "[email protected]"
    "id": "u0005",
    "name": "Chelsey Dietrich",
    "username": "kamren",
    "email": "[email protected]"

Creating Controllers

Subsequent are controllers. One simple means to consider controllers is to think about features used to course of requests on API endpoints. When your React app fetch some endpoint the response shall be created by these features, or controllers. For now, we’ll create two controllers, one for dwelling (/api endpoint) and one for customers (/customers endpoint).

The controller for dwelling shall be quite simple. It is going to include just one operate. This operate shall be used to course of GET request to /api endpoint. As a response, it can ship a easy message. That is the welcome message displayed in React app after App part mounts. It’s the place we use .textual content() to course of the info from API.

// server/controllers/home-controller.js

// Create controller for GET request to '/api'
exports.homeGet = async (req, res) => {
  res.ship('Welcome again commander.')

Controller for customers will appear to be the earlier. It is going to include one features to course of GET requests. It is going to course of request to /customers/all endpoint. It is going to take the listing of customers, saved in customers.json, and ship it in json format as a response. That is the info we use to render the desk of customers. Additionally it is the place we use .json() to course of the info from API.

// server/controllers/home-controller.js

// Import json with listing of customers
const customers = require('./../information/customers.json')

// Create controller for GET request to '/customers/all'
exports.usersGetAll = async (req, res) => {
  // res.ship('There shall be dragons, not posts.')

Creating Routes

When we have now controllers. Now, we have to create routes. These routes will use particular controllers on particular API endpoints. Each request the React sends first goes by means of a route created for particular endpoint and sort of request. It then applies right controller that then handles the response.

We might want to create two routes, one for dwelling (/api endpoint) and one for customers (/customers endpoint). In every router, we’ll import specific framework and use it to create new router. We are going to then use this router, and get technique, to will deal with GET request coming to / endpoint.

Additionally it is this router technique, get on this case, that specifies which controller needs to be used on which endpoint. For the house (/api endpoint) we’ll set the router technique to make use of the homeGet controller. As the very last thing, we’ll export the router so we will later import it and use it in primary server file.

// Import specific
const specific = require('specific')

// Import dwelling controller
const homeControllers = require('../controllers/home-controller.js')

// Create specific router
const router = specific.Router()

// Create rout between homeControllers and '/' endpoint
router.get('/', homeControllers.homeGet)

// Export router
module.exports = router

The router for customers (/customers endpoint) will look virtually just like the endpoint for dwelling (/api). The distinction is that now we’ll import usersController and usersGetAll() controller we created beforehand. Then, we’ll create new route for /all endpoint.

One necessary factor to recollect is that we don’t use /customers/all right here, however solely /all although we are literally creating route for /customers/all. The reason being that after we implement this router within the specific app, in server.js, we implement it for /customers endpoint.

The results of that is that every one customers routes outlined right here shall be principally “prefixed” with “/customers”. So, if we create route for /all endpoint right here it can develop into /customers/all. Categorical will robotically add the “/customers” to the /all route.

For this reason, within the React app, we fetch /customers/all endpoint as a substitute of fetching /all endpoint and it really works.

// Import specific
const specific = require('specific')

// Import customers controller
const usersController = require('./../controllers/users-controller.js')

// Create specific router
const router = specific.Router()

// Create rout between usersController and '/all' endpoint
// Be aware:
// Foremost route (in server.js) for customers
// is ready to '/customers'
// Which means all customers routes
// shall be prefixed with /customers'
// i.e.: '/all' will develop into '/customers/all'
router.get('/all', usersController.usersGetAll)

// Export router
module.exports = router

Constructing the server

You’re within the finale. That is the very last thing we have to do to get our specific server up and working. Now, we have to do few issues. First, we’ll import specific framework and middleware dependencies. Subsequent, we import each routers, for dwelling and customers. After that, we’ll create variable for default port and create specific app.

When we have now this we will implement all middleware we have now. We are able to do that through the use of app and its use() technique. Right here, middleware is handed as an argument. One factor to recollect. We have to implement middleware earlier than we implement routes, if we wish the middleware to be utilized on these routes. Put merely, middleware must be positioned above routes.

Once we are achieved with making use of middleware we will implement each routers. We do that additionally through the use of app and its use() technique. Within the case of routers, we’ll move two arguments. The primary would be the endpoint, i.e. /api and /customers. The second argument shall be router that needs to be used on every route.

The very last thing we have now to do is to launch this specific server. That is achieved through the use of app and hear() technique. This technique takes one parameter, which is a port the place the server needs to be working. You too can move non-obligatory callback operate. This may be helpful for logging message that claims that server began and the place.

// Import specific framework
const specific = require('specific')

// Import middleware
const bodyParser = require('body-parser')
const cookieParser = require('cookie-parser')
const compression = require('compression')
const helmet = require('helmet')
const cors = require('cors')

// Import routes
const homeRouter = require('./routes/home-route')
const usersRouter = require('./routes/users-route')

// Setup default port
const PORT = course of.env.PORT || 4000

// Create specific app
const app = specific()

// Implement middleware
app.use(specific.urlencoded({ prolonged: false }))

if (course of.env.NODE_ENV && course of.env.NODE_ENV !== 'development') {
    app.get('*', (req, res) => {
      res.sendFile('construct/index.html', { root: __dirname })

// Implement route for '/api' endpoint
app.use('/api', homeRouter)

// Implement route for '/customers' endpoint
// ! Be aware:
// '/customers' will prefix all publish routes
// with '/customers' => '/all' will develop into '/customers/all'
app.use('/customers', usersRouter)

// Implement route for errors
app.use((err, req, res, subsequent) => {

   res.standing(500).ship('One thing broke!')

// Begin specific app
app.hear(PORT, operate() {
  console.log(`Server is working on: ${PORT}`)

Conclusion: How one can Construct React app With Categorical API

Congratulations, you’ve simply constructed your individual React app with specific! I hope you loved this tutorial. Let’s shortly recap what you probably did right this moment. As the very first thing, you created a easy React app. On this app, you created features and used them, together with React hooks, to fetch information from totally different API endpoints and displayed these information.

Subsequent, you prolonged the create-react-app boilerplate workflow with new scripts, dependencies and proxy. After that, you constructed the specific server. You’ve created controllers, routes and applied them, together with middleware, in your specific app. Now, begin your new React specific app with npm run begin or yarn begin and construct one thing.

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