dhbw: neuer kurs technik I — 4 kapitel + demo assets

slides/dhbw/03_nodejs_basics.md

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+---
+marp: true
+theme: gaia
+paginate: true
+backgroundColor: #fff
+header: "Web Engineering – DHBW Stuttgart"
+footer: "Michael Czechowski – SoSe 2025"
+---
+
+<style>
+:root {
+  --color-foreground: #1a1a2e;
+  --color-highlight: #005f8a;
+  --color-dimmed: #4a6a7a;
+}
+section.invert {
+  --color-foreground: #fff;
+}
+section {
+  font-size: 1.7rem;
+}
+h1 {
+  color: #005f8a;
+}
+section.invert h1 {
+  color: #fff;
+}
+pre {
+  background: #0f1e2e;
+  color: #00b4d8;
+  border-radius: 8px;
+  border-left: 3px solid #005f8a;
+}
+pre code {
+  background: transparent;
+  color: inherit;
+}
+code {
+  background: #1a3a4a;
+  color: #00b4d8;
+  padding: 0.15em 0.4em;
+  border-radius: 4px;
+}
+a {
+  color: var(--color-highlight);
+}
+</style>
+
+<!-- _class: invert -->
+<!-- _header: '' -->
+<!-- _backgroundColor: #001520 -->
+
+# Node.js – Scripting, Running and Building
+
+---
+
+# Node.js – Was ist das?
+
+- JavaScript Runtime (V8 Engine)
+- Server-side JavaScript
+- npm Package Manager
+- Ideal für: APIs, CLI Tools, Automation
+
+---
+
+<!-- _header: '' -->
+<!-- _footer: '' -->
+
+![bg fit](./assets/demos/nodejs-usecases.png)
+
+
+---
+
+# node --check und node -e
+
+```bash
+# Syntax check only
+node --check script.js
+
+# One-liner
+node -e "console.log('Hallo Welt')"
+```
+
+---
+
+# node -e Beispiele
+
+```bash
+# String
+node -e "console.log('Hello ' + process.argv[2])" Welt
+
+# File reading
+node -e "console.log(require('fs').readFileSync('data.json'))"
+
+# JSON parsen
+node -e "console.log(JSON.parse(process.argv[1]))" '{"a":1}'
+```
+
+---
+
+# require() – Module laden
+
+```javascript
+// Eigene Datei
+const utils = require('./utils');
+
+// npm Modul
+const express = require('express');
+
+// Built-in
+const fs = require('fs');
+const path = require('path');
+```
+
+---
+
+# __dirname und __filename
+
+```javascript
+// Aktuelles Verzeichnis (Node.js)
+console.log(__dirname);   // /home/user/project/src
+console.log(__filename);  // /home/user/project/src/app.js
+
+// Pfad joinen
+const configPath = path.join(__dirname, '..', 'config.json');
+```
+
+---
+
+# HTTP Server mit Node.js (Built-in)
+
+```javascript
+const http = require('http');
+
+const server = http.createServer((req, res) => {
+  res.writeHead(200, { 'Content-Type': 'text/html' });
+  res.end('<h1>Hallo Welt!</h1>');
+});
+
+server.listen(3000, () => {
+  console.log('Server läuft auf Port 3000');
+});
+```
+
+---
+
+# fs – Dateien lesen/schreiben
+
+```javascript
+const fs = require('fs');
+
+// Async
+fs.readFile('data.json', 'utf8', (err, data) => {
+  if (err) throw err;
+  console.log(JSON.parse(data));
+});
+
+// Sync
+const content = fs.readFileSync('data.json', 'utf8');
+
+// Write
+fs.writeFile('output.txt', 'Hallo Welt', (err) => {
+  if (err) throw err;
+});
+```
+
+---
+
+# package.json – Das Herzstück
+
+```json
+{
+  "name": "mein-projekt",
+  "version": "1.0.0",
+  "main": "index.js",
+  "scripts": {
+    "start": "node index.js",
+    "dev": "node --watch index.js",
+    "test": "node --test"
+  },
+  "dependencies": {
+    "express": "^4.18.0"
+  },
+  "devDependencies": {
+    "nodemon": "^3.0.0"
+  }
+}
+```
+
+---
+
+# npm Scripts
+
+```bash
+# npm run <script>
+npm run start
+npm run dev
+
+# Mit Argumenten
+npm run build -- --production
+
+# Lifecycle scripts
+npm install  → postinstall
+npm start    → start (direkt)
+```
+
+---
+
+# Node.js Module – exports
+
+```javascript
+// utils.js
+module.exports = {
+  add: (a, b) => a + b,
+  greet: (name) => `Hallo ${name}!`
+};
+
+// Oder einzelne Exporte
+module.exports.add = (a, b) => a + b;
+```
+
+---
+
+# Fragen?
+
+1. Wie startest du einen Node.js Server auf Port 8080?
+2. Was macht `node --check`?
+3. Wozu dient `package.json`?