Route parameters in Express - Mini Project: Build & Apply

Express Route Parameters

📖 Scenario: You are building a simple web server that responds to user requests for product details. Each product has a unique ID, and you want to capture this ID from the URL to show the right product information.

🎯 Goal: Create an Express server that uses route parameters to capture a product ID from the URL and respond with a message showing that ID.

📋 What You'll Learn

Create an Express app instance

Define a route with a route parameter named productId

Use the route parameter to send a response including the productId

Start the server listening on port 3000

💡 Why This Matters

🌍 Real World

Web servers often use route parameters to capture dynamic parts of URLs, like user IDs or product IDs, to serve personalized content.

💼 Career

Understanding route parameters is essential for backend developers working with Express or similar web frameworks to build RESTful APIs.

1

Set up Express app

Write code to import express and create an Express app instance called app.

Express

const express = require('express');
// Your code here

Need a hint?

Use require('express') to import Express and then call it to create app.

2

Define route parameter

Add a GET route on app for path /product/:productId that takes req and res as parameters.

Express

const express = require('express');
const app = express();

// Your code here

Need a hint?

Use app.get with the path /product/:productId and a callback with req and res.

3

Use route parameter in response

Inside the route handler, get the productId from req.params.productId and send a response with the text Product ID is: <productId> using res.send().

Express

const express = require('express');
const app = express();

app.get('/product/:productId', (req, res) => {
  // Your code here
});

Need a hint?

Access the route parameter with req.params.productId and use template strings to send it back.

4

Start the server

Add code to make the app listen on port 3000 and log 'Server running on port 3000' when it starts.

Express

const express = require('express');
const app = express();

app.get('/product/:productId', (req, res) => {
  const productId = req.params.productId;
  res.send(`Product ID is: ${productId}`);
});

// Your code here

Need a hint?

Use app.listen(3000, () => { ... }) and inside the callback log the message.