uni/slides/dhbw/04_nodejs_advanced.md

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true	gaia	true		Web Engineering – DHBW Stuttgart	Michael Czechowski – SoSe 2026

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Web Engineering

DHBW Stuttgart · Informatik / Wirtschaftsinformatik

Sommersemester 2026 · Sitzung 5 — Express API, CRUD und Middlewares

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Ressourcen zum Selbstlernen

• CODE CRISPIES — codecrispi.es
• Online Code-Editor — codepen.io
• MDN (Mozilla Developer Network) — developer.mozilla.org/de/
• Flexbox-Spiel — flexboxfroggy.com
• Grid-Spiel — cssgridgarden.com

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Inhalt

1. Node.js — Fun Facts & alternative Runtimes
2. process — Signal-Handling, Graceful Shutdown
3. Express — Setup, Routing
4. Middlewares (eigene + built-in)
5. CRUD-Endpunkte (Create, Read, Update, Delete)
6. Error Handling
7. WebSockets

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Node.js – Advanced

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node.js – Fun Facts

• Entwickelt von Ryan Dahl in 2009
• Erste serverseitige Laufzeitumgebung in JavaScript (C++)
• Inspiriert von Nginx (Non-blocking I/O)

Alternativen heute:

• Deno (2020): Rust, Tokio
• Bun (2022): Zig

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process – Prozess-Steuerung

process.on("SIGINT", () => {
  console.log("Received SIGINT. Closing server...");
  server.close(() => {
    console.log("Server closed.");
    process.exit(0);
  });
});

// Signale
process.exit(0);  // Erfolgreich
process.exit(1);  // Fehler

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node.js Module System

// ES Modules (modern, "type": "module")
import express from "express";
import { port } from "./src/config/constants.js";
import { readFileSync } from "node:fs";

// CommonJS (legacy)
const express = require("express");
const fs = require("fs");

→ Neue Projekte: ESM. Built-ins immer mit node:-Präfix.

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HTTP Request mit node-fetch

// Node.js 18+ hat fetch eingebaut
const res = await fetch('https://api.example.com/data');
const data = await res.json();

// Ältere Versionen: node-fetch
import fetch from 'node-fetch';

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Web Server, Builder, Bundler

# Boilerplates erstellen
npm create vite@latest my-app -- --template react
npm create svelte@latest
npm create astro@latest

# nuxt
npm install nuxt
npm run dev

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Express – Grundlagen

import express from 'express';
const app = express();

app.listen(port, () => {
  console.log(`Server läuft auf Port ${port}`);
});

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Express – Middleware

app.use(express.json());

app.use('/api', (req, res, next) => {
  console.log('Time:', Date.now());
  next();
});

app.use((req, res, next) => {
  console.log('Middleware 2');
  next();
});

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Express – CRUD Routes

app.get('/api/:key', async (req, res) => {
  const context = cache.get(req.params.key);
  res.json({ context });
});

app.post('/api/:key', async (req, res) => {
  const payload = req.body;
  res.json({ created: cache.set(req.params.key, payload) });
});

app.put('/api/:key', async (req, res) => {
  const payload = req.body;
  res.json({ updated: cache.update(req.params.key, payload) });
});

app.delete('/api/:key', async (req, res) => {
  cache.remove(req.params.key);
  res.json({ deleted: req.params.key });
});

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Express – server.listen

const server = app.listen(port, () => {
  console.log(`Server läuft auf Port ${port}`);
});

server.on('error', (err) => {
  console.error('Server error:', err);
});

server.close(() => {
  console.log('Server geschlossen');
});

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WebSockets

import { WebSocketServer } from 'ws';

const wss = new WebSocketServer({ port: 8080 });

wss.on('connection', (ws) => {
  console.log('Client verbunden');

  ws.on('message', (data) => {
    console.log('Empfangen:', data.toString());
    ws.send('Pong');
  });
});

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