Express.js Live Demo

This page is served by an Express.js server. Compare how much simpler this code is versus the raw Node.js demo in Module 02!

Reading Request Data in Express

Headers (req.headers / req.get())

Header	Value	Express Access
Your IP	10.1.38.156	req.ip or req.headers['x-forwarded-for']
User-Agent	Mozilla/5.0 AppleWebKit/537.36 (KHTML, like Gecko; compatible; ClaudeBot/1.0; +claudebot@anthropic.com)	req.get('user-agent')
Accept-Language	not sent	req.get('accept-language')
Host	cse135.site:3002	req.get('host')

Query String (req.query)

No query parameters. Try: /demo?name=YourName&course=CSE135

Try Query Strings:
Send as GET (req.query)

Route Parameters (req.params)

Try these routes with parameters:

• /users/42 - req.params.id = "42"
• /posts/2024/01 - req.params.year = "2024", req.params.month = "01"

Request Body (req.body)

POST data is available in req.body after middleware parses it:

Try POST (form-urlencoded):
Send as POST (req.body)

Try POST (JSON):
{"name": "Alice", "items": [1, 2, 3]} Send as JSON (req.body)

API Response

Compare: Raw Node.js vs Express

Task	Raw Node.js	Express
Query string	url.parse(req.url, true).query	req.query
Headers	req.headers['user-agent']	req.get('user-agent')
POST body	Manual stream collection	req.body (with middleware)
Route params	Manual URL parsing	req.params
Send JSON	res.writeHead(); res.end(JSON.stringify())	res.json()

The Code Behind This

View the source: express-demo.js

Back to Module 03