res.json for JSON responses in Express - Mini Project: Build & Apply

Using res.json for JSON responses in Express

📖 Scenario: You are building a simple Express server that sends JSON data to clients. This is common when creating APIs that share data with web or mobile apps.

🎯 Goal: Create an Express server that responds with JSON data using res.json(). You will set up data, configure a route, send the JSON response, and complete the server setup.

📋 What You'll Learn

Create a data object with exact key-value pairs

Set up an Express app and a port variable

Create a GET route that sends the data as JSON using res.json()

Start the server listening on the specified port

💡 Why This Matters

🌍 Real World

APIs often send data as JSON to web or mobile apps. Using res.json() in Express is a simple way to send this data.

💼 Career

Backend developers use Express and res.json() to build APIs that communicate data efficiently and clearly.

1

DATA SETUP: Create the data object

Create a constant called userData with this exact object: { name: "Alice", age: 30, city: "Wonderland" }

Express

// Create the userData object with name, age, and city
// Your code here

Need a hint?

Use const to create an object with the keys name, age, and city.

2

CONFIGURATION: Set up Express app and port

Write these two lines: const express = require('express'); and const app = express(); Then create a constant port set to 3000

Express

const userData = { name: "Alice", age: 30, city: "Wonderland" };
// Set up Express and port
// Your code here

Need a hint?

Use require('express') to import Express, then create the app and port variables.

3

CORE LOGIC: Create GET route sending JSON response

Use app.get with path "/user" and a callback with parameters req and res. Inside, send userData as JSON using res.json(userData).

Express

const userData = { name: "Alice", age: 30, city: "Wonderland" };
const express = require('express');
const app = express();
const port = 3000;

// Create GET route for /user that sends userData as JSON
// Your code here

Need a hint?

Use app.get with the path "/user" and send the userData object as JSON with res.json().

4

COMPLETION: Start the server listening on the port

Add app.listen(port, () => { console.log(`Server running on port ${port}`); }); to start the server.

Express

const userData = { name: "Alice", age: 30, city: "Wonderland" };
const express = require('express');
const app = express();
const port = 3000;

app.get('/user', (req, res) => {
    res.json(userData);
});

// Start the server listening on port
// Your code here

Need a hint?

Use app.listen with the port variable and a callback that logs the server start message.