JavaScript Lab: Exploring REST APIs

Let's dive deep into exploring REST APIs by setting up a Node.js server that uses object literals to simulate a simple JSON database.
We'll also create a client-side program to exercise various aspects of REST, such as CRUD (Create, Read, Update, Delete) operations.

Lab Exercise: Deep Dive into REST APIs

Objective: - Understand and implement RESTful principles. - Create a Node.js server with object literals simulating a JSON database. - Develop a client-side program to perform CRUD operations on the server.

Part 1: Setting Up the Node.js Server

1. Initialize the Project** 1. Create a new directory for the project and navigate into it: ```bash mkdir rest-api-lab cd rest-api-lab ```
2. Initialize a new Node.js project: ```bash npm init -y ```
3. Install the required dependencies: ```bash npm install express ```

2. Create the Server

1. Create a file named `server.js`: ```javascript ```
2. Run the server: ```bash node server.js

Updated Corrected Code remember to npm i cors

const express = require('express');
const cors = require('cors');
const app = express();
const port = 3000;


let items = [
{ id: 1, name: 'Item 1', description: 'Description of Item 1' },
{ id: 2, name: 'Item 2', description: 'Description of Item 2' },
{ id: 3, name: 'Item 3', description: 'Description of Item 3' }
];'/items', (req, res) => {
const newItem = {
id: items.length + 1,
description: req.body.description

app.get('/items', (req, res) => {

app.get('/items/:id', (req, res) => {
const item = items.find(i => === parseInt(;
if (!item) return res.status(404).send('Item not found');

app.put('/items/:id', (req, res) => {
const item = items.find(i => === parseInt(;
if (!item) return res.status(404).send('Item not found'); =;
item.description = req.body.description;

app.delete('/items/:id', (req, res) => {
const itemIndex = items.findIndex(i => === parseInt(;
if (itemIndex === -1) return res.status(404).send('Item not found');

items.splice(itemIndex, 1);

app.listen(port, () => {
console.log(`Server running at http://localhost:${port}`);


- Explain the use of Express for setting up the server. - Discuss the use of object literals to simulate a JSON database. - Walk through each CRUD endpoint and its implementation.

Part 2: Creating the Client-Side Application

1. Create the HTML File
1. Create a file named `index.html`: ```html <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>REST API Client</title> <style> body { font-family: Arial, sans-serif; } .container { max-width: 600px; margin: 0 auto; } input, button { display: block; width: 100%; margin-bottom: 10px; padding: 10px; } button { background-color: #4CAF50; color: white; border: none; cursor: pointer; } button:hover { background-color: #45a049; } </style> </head> <body> <div class="container"> <h1>REST API Client</h1> <h2>Create Item</h2> <input type="text" id="createName" placeholder="Name"> <input type="text" id="createDescription" placeholder="Description"> <button onclick="createItem()">Create</button>
<h2>Read Items</h2> <button onclick="getItems()">Get All Items</button> <ul id="itemsList"></ul>
<h2>Read Single Item</h2> <input type="number" id="readId" placeholder="Item ID"> <button onclick="getItem()">Get Item</button> <p id="singleItem"></p>
<h2>Update Item</h2> <input type="number" id="updateId" placeholder="Item ID"> <input type="text" id="updateName" placeholder="New Name"> <input type="text" id="updateDescription" placeholder="New Description"> <button onclick="updateItem()">Update</button>
<h2>Delete Item</h2> <input type="number" id="deleteId" placeholder="Item ID"> <button onclick="deleteItem()">Delete</button> </div>
<script> function createItem() { const name = document.getElementById('createName').value; const description = document.getElementById('createDescription').value; fetch('/items', { method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ name, description }) }) .then(response => response.json()) .then(data => { alert(`Item created: ${}`); getItems(); }) .catch(error => console.error('Error:', error)); }
function getItems() { fetch('/items') .then(response => response.json()) .then(data => { const itemsList = document.getElementById('itemsList'); itemsList.innerHTML = ''; data.forEach(item => { const listItem = document.createElement('li'); listItem.textContent = `${}. ${}: ${item.description}`; itemsList.appendChild(listItem); }); }) .catch(error => console.error('Error:', error)); }
function getItem() { const id = document.getElementById('readId').value; fetch(`/items/${id}`) .then(response => response.json()) .then(data => { document.getElementById('singleItem').textContent = `Name: ${}, Description: ${data.description}`; }) .catch(error => console.error('Error:', error)); }
function updateItem() { const id = document.getElementById('updateId').value; const name = document.getElementById('updateName').value; const description = document.getElementById('updateDescription').value; fetch(`/items/${id}`, { method: 'PUT', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify({ name, description }) }) .then(response => response.json()) .then(data => { alert(`Item updated: ${}`); getItems(); }) .catch(error => console.error('Error:', error)); }
function deleteItem() { const id = document.getElementById('deleteId').value; fetch(`/items/${id}`, { method: 'DELETE' }) .then(() => { alert('Item deleted'); getItems(); }) .catch(error => console.error('Error:', error)); } </script> </body> </html> ```

Explanation - Walk through the HTML structure, focusing on the forms and buttons for each CRUD operation. - Explain how the JavaScript functions use the Fetch API to send requests to the server. - Discuss how responses are handled and the DOM is updated.

Part 3: Running and Testing the Project

1. Ensure the server is running: ```bash node server.js ```
2. Open the `index.html` file in a browser (you can use a local server like `http-server` for this): npx http-server -c-1 -o

3. Test each functionality (Create, Read, Update, Delete) using the form inputs and buttons.


- Recap the RESTful principles demonstrated:
stateless interactions, use of standard HTTP methods, and structured URLs. - Highlight how the client-side application interacts with the server. - Discuss potential improvements, such as form validation and better error handling.
#### **Extensions and Future Enhancements:** - **Form Validation:** Add client-side validation to ensure all inputs are filled out correctly. - **Error Handling:** Improve error handling to provide more detailed feedback to users. - **UI Enhancements:** Enhance the user
interface with better styling and user experience features.
This lab exercise provides a comprehensive hands-on approach to understanding and implementing REST APIs, making it practical and engaging for students.
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