Express.md

Setting up a Basic RESTful Server with Node.js and Express

Table of contents

Introduction

Prerequisites

Setting up the project

Installing Express

Creating a basic server

Defining RESTful routes

Additional Resources

Introduction

This guide will help you set up a simple RESTful server using Express, a popular web framework for Node.js. We will create a basic server that listens for HTTP requests and sends responses.

Prerequisites

Node.js
npm

Setting up the project

Express Getting Started

First, let's create a new directory for our project and navigate to it using the terminal.

mkdir express-server
cd express-server

Now, initialize the project with the npm init command. Follow the prompts or use npm init -y to accept the defaults.

npm init -y

Installing Express

To install Express, run the following command:

npm install express

Creating a basic server

Create a new file named app.js in the project directory and add the following code:

const express = require("express");
const app = express();
const PORT = process.env.PORT || 3000;

app.get("/", (req, res) => {
  res.send("Hello, World!");
});

app.listen(PORT, () => {
  console.log(`Server is running on port ${PORT}`);
});

This code imports the Express library, creates an instance of it, and sets up a basic server that listens on port 3000.

Defining RESTful routes

Next, we'll define some RESTful routes for a simple resource. For this example, we'll use an in-memory array to represent a list of items.

Add the following code to app.js:

const items = [];

app.use(express.json());

app.get("/items", (req, res) => {
  res.json(items);
});

app.post("/items", (req, res) => {
  const newItem = req.body;
  items.push(newItem);
  res.status(201).json(newItem);
});

app.get("/items/:id", (req, res) => {
  const id = parseInt(req.params.id);
  const item = items.find((i) => i.id === id);

  if (!item) {
    return res.status(404).json({ error: "Item not found" });
  }

  res.json(item);
});

app.put("/items/:id", (req, res) => {
  const id = parseInt(req.params.id);
  const index = items.findIndex((i) => i.id === id);

  if (index === -1) {
    return res.status(404).json({ error: "Item not found" });
  }

  items[index] = req.body;
  res.json(items[index]);
});

app.delete("/items/:id", (req, res) => {
  const id = parseInt(req.params.id);
  const index = items.findIndex((i) => i.id === id);

  if (index === -1) {
    return res.status(404).json({ error: "Item not found" });
  }

  const deletedItem = items.splice(index, 1)[0];
  res.json(deletedItem);
});

We have defined the following routes for our items resource:

GET /items: Retrieve all items
POST /items: Create a new item
GET /items/:id: Retrieve a specific item by ID
PUT /items/:id: Update an existing item by ID
DELETE /items/:id: Delete an item by ID
The app.use(express.json()); line tells Express to parse incoming JSON payloads, allowing us to access the request body data.

Additional Resources

Official Reference
GitHub Page
MDN Express Example
Tutorialspoint