dhbw 03-04 (node.js basics+advanced): cjs → esm in code-beispielen (import + node:-präfix), legacy-cjs als vergleichsbeispiel markiert, einheitliche cover, font 1.7→1.4rem, fragen-slides raus, __dirname/__filename via import.meta.url
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@@ -17,7 +17,7 @@ section.invert {
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--color-foreground: #fff;
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}
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section {
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font-size: 1.7rem;
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font-size: 1.4rem;
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}
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h1 {
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color: #005f8a;
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@@ -50,6 +50,30 @@ a {
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<!-- _header: '' -->
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<!-- _backgroundColor: #001520 -->
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# Web Engineering
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**DHBW Stuttgart** · Informatik / Wirtschaftsinformatik
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**Sommersemester 2026** · Sitzung 4 — Node.js: Scripting, Running and Building
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---
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# Inhalt
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1. Node.js: was und warum
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2. `node --check`, `node -e` (One-Liner)
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3. Module: `require` / `import`, `__dirname` / `__filename`
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4. HTTP-Server (built-in)
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5. `fs` — Dateien lesen / schreiben
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6. `package.json` — Aufbau und Lifecycle
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7. npm Scripts
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8. Module exportieren
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---
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<!-- _class: invert -->
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<!-- _backgroundColor: #001520 -->
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# Node.js – Scripting, Running and Building
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---
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@@ -89,8 +113,10 @@ node -e "console.log('Hallo Welt')"
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# String
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node -e "console.log('Hello ' + process.argv[2])" Welt
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# File reading
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node -e "console.log(require('fs').readFileSync('data.json'))"
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# File reading (ESM via --input-type)
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node --input-type=module -e \
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"import { readFileSync } from 'node:fs'; \
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console.log(readFileSync('data.json', 'utf8'))"
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# JSON parsen
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node -e "console.log(JSON.parse(process.argv[1]))" '{"a":1}'
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@@ -98,70 +124,81 @@ node -e "console.log(JSON.parse(process.argv[1]))" '{"a":1}'
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---
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# require() – Module laden
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# Module laden – ESM (modern)
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`"type": "module"` in `package.json` einschalten.
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```javascript
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// Eigene Datei
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const utils = require('./utils');
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// Eigene Datei (Endung .js erforderlich!)
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import { add, greet } from "./utils.js";
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// npm Modul
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const express = require('express');
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// npm Modul (default + named import)
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import express from "express";
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import { Router } from "express";
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// Built-in
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const fs = require('fs');
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const path = require('path');
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// Built-in (mit "node:"-Präfix)
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import { readFileSync } from "node:fs";
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import { join } from "node:path";
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```
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<small>**Legacy CJS:** `const express = require("express")` — funktioniert noch, aber ESM ist heute Standard.</small>
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---
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# __dirname und __filename
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# Pfad-Auflösung in ESM
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```javascript
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// Aktuelles Verzeichnis (Node.js)
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console.log(__dirname); // /home/user/project/src
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console.log(__filename); // /home/user/project/src/app.js
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import { fileURLToPath } from "node:url";
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import { dirname, join } from "node:path";
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// Pfad joinen
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const configPath = path.join(__dirname, '..', 'config.json');
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const __filename = fileURLToPath(import.meta.url);
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const __dirname = dirname(__filename);
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const configPath = join(__dirname, "..", "config.json");
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```
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<small>In ESM gibt es **kein** automatisches `__dirname` / `__filename` (anders als CJS). Über `import.meta.url` rekonstruieren.</small>
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---
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# HTTP Server mit Node.js (Built-in)
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**ESM** (modern, `"type": "module"` in `package.json`):
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```javascript
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const http = require('http');
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import { createServer } from "node:http";
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const server = http.createServer((req, res) => {
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res.writeHead(200, { 'Content-Type': 'text/html' });
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res.end('<h1>Hallo Welt!</h1>');
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const server = createServer((req, res) => {
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res.writeHead(200, { "Content-Type": "text/html" });
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res.end("<h1>Hallo Welt!</h1>");
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});
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server.listen(3000, () => {
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console.log('Server läuft auf Port 3000');
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console.log("Server läuft auf Port 3000");
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});
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```
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<small>**CommonJS** (legacy): `const http = require("http");` — funktioniert noch, aber neue Projekte nutzen ESM.</small>
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---
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# fs – Dateien lesen/schreiben
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```javascript
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const fs = require('fs');
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import { readFile, readFileSync, writeFile } from "node:fs";
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import { readFile as readFileAsync } from "node:fs/promises";
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// Async
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fs.readFile('data.json', 'utf8', (err, data) => {
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// Promise-API (empfohlen, modern)
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const data = await readFileAsync("data.json", "utf8");
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console.log(JSON.parse(data));
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// Callback-API
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readFile("data.json", "utf8", (err, data) => {
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if (err) throw err;
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console.log(JSON.parse(data));
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});
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// Sync
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const content = fs.readFileSync('data.json', 'utf8');
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// Write
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fs.writeFile('output.txt', 'Hallo Welt', (err) => {
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if (err) throw err;
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});
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// Sync (nur für Setup / Scripts)
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const content = readFileSync("data.json", "utf8");
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```
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---
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@@ -206,23 +243,26 @@ npm start → start (direkt)
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---
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# Node.js Module – exports
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# Node.js Module – exports (ESM)
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```javascript
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// utils.js
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module.exports = {
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add: (a, b) => a + b,
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greet: (name) => `Hallo ${name}!`
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};
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// utils.js — named exports
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export const add = (a, b) => a + b;
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export const greet = (name) => `Hallo ${name}!`;
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// Oder einzelne Exporte
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module.exports.add = (a, b) => a + b;
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// utils.js — default export
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export default {
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add,
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greet
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};
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```
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---
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```javascript
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// nutzen
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import { add, greet } from "./utils.js"; // named
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import utils from "./utils.js"; // default
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import utils, { add } from "./utils.js"; // beides
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```
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# Fragen?
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<small>**Legacy CJS:** `module.exports = { add, greet }` + `const { add } = require("./utils")`.</small>
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1. Wie startest du einen Node.js Server auf Port 8080?
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2. Was macht `node --check`?
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3. Wozu dient `package.json`?
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