API Development with Node.js and Express

This Tutorial is about how to handle API Routes inside of a Node.js and Express Project.

Definition of Routing

Routing or router in web development is a mechanism where HTTP requests are routed to the code that handles them. In Other Words in the Router you determine what should happen when a user visits a certain page. When you want to show a User a Message , we may do something like

const express = require("express");
const app = express();
app.get("/", (request, response) => {
  res.send("Hello, User");

We can use other HTTP Request methods such as post, put , delete, patch.

you can see all list of Express methods here

Project Setup

you can run the Following Steps in your Terminal

// Create a new folder for our project
mkdir node-express-routes
// Change Directory
cd node-express-routes
// Initialise a new Node project
npm init -y
// Create our entry file
touch index.js
// Install Express
npm install express --save
// nodemon will also be installed in Dependencies
npm install -D nodemon

Nodemon is helpful because you don't have to restard the Server once you changed something in a File

you can now run npm start or yarn start and your Project will be up und running inside of the Terminal.

Routes with Express

we can now create our Express Application and run it on a Port that we specify

const express = require("express");
const app = express();
const PORT = 3000;
app.listen(PORT, () =>
  console.log(`Express server currently running on port ${PORT}`),

Now you can add your First Route with a default Get route.

app.get(`/`, (request, response) => {
  response.send("Hello, /");

We are using app.get() because we want a route handler for the / route. The request variable contains Infos about the request, we are able to esponde back to the HTTP request with response .Here we are sending just a simple text back to the browser , we can modify this to send HTML instead . This will work because response.send() can take either a Buffer object , a String or an Array . Express handles these Inputs differently and changes the content-type header to match, in our case its set to text/html

Route Parameters

you can now create a new route at app.get(/users) and app.get(users/:id)

with some Mock Data :

const users = [
    id: 1,
    username: "User1",
    role: "a",
    id: 2,
    username: "User2",
    role: "b",
    id: 3,
    username: "User3",
    role: "c",
app.get(`/users`, (request, response) => {

app.get(`/users/:id`, (request, response) => {
  const userId = Number(;
  const getUser = users.find((account) => === userId);

  if (!getUser) {
    response.status(400).send("Account not found.");
  } else {

we are now able to use users/:id to filter our users. When we describe a route that has a :parameter, Express will consider this as a user input and match for that

for /users we will get all our users , but for /users/id we will only get one user

BodyParser Middleware

we can add a new Route using which uses the request body to add new items to our array. In order to parse the incoming body content , we will need to install the body-parser middleware

npm install --save body-parser

next , tell express that we want to use the bodyparser

const bodyParser = require("body-parser");
app.use(bodyParser.urlencoded({ extended: false }));

Post Request

defining'/users')route, will allow us to push the incoming body content into our users array.`/users`, (request, response) => {
  const incomingAccount = request.body;



We can use Postman to send a Post Request with a specific JSON body content

Maher Gallaoui

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