🟢 Node.js Intro

Chapter: Node.js & Express — Backend APIs · Level ★★☆ · Time: 15 min

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NameClassDate

After this worksheet you can

Explain what Node.js isDescribe the event loopUse the http moduleUnderstand npm's role

📚 Quick Recap

🎯 What you'll practice: Node's runtime, the event loop, and building a raw HTTP server.

🧮 Section B · Problem Solving ● INTERMEDIATE 2 + 3×3 = 11

5The method that starts a server listening for connections is server.().

6http.createServer() takes a callback with (req, ) parameters.

7Write a minimal Node server that responds "Hello!" to every request on port 3000.

8What does res.writeHead(200, {...}) do?

9Why does the next lesson introduce Express instead of continuing with raw http?

🚀 Section C · Challenge ● CHALLENGE 5

10Explain why Node's non-blocking model lets a single thread handle thousands of concurrent connections, using a file-read request as an example.

💭 Reflection — the most useful thing I learned:

A ___/4 B ___/11 C ___/5 Total ___/20 Teacher's Signature Parent's Signature

✂ answer key — fold or cut before handing out

1-A 2-B 3-B 4-B | 5 = listen 6 = res 7 = const http=require('http');http.createServer((req,res)=>{res.end('Hello!');}).listen(3000); 8 = It sets the HTTP status code and response headers before the body is sent 9 = Because manually writing routing, JSON parsing, and error handling with raw http gets repetitive fast — Express wraps the same server pattern in a much simpler, higher-level API | 10 = When a request triggers a file read, Node hands the disk operation off to the OS/background thread pool and immediately moves on to handle other incoming requests; when the file read finishes, its callback is queued and run on the single main thread — so the thread is never sitting idle waiting on slow I/O.

📄 Need offline practice?Print this worksheet or open the one-page cheat sheet.

🗒 Cheat Sheet

🧠 Section A · Concept Check ● BEGINNER 4 × 1 = 4

🧮 Section B · Problem Solving ● INTERMEDIATE 2 + 3×3 = 11

🚀 Section C · Challenge ● CHALLENGE 5