---
marp: true
theme: gaia
paginate: true
backgroundColor: #fff
header: "Web Engineering – DHBW Stuttgart"
footer: "Michael Czechowski – SoSe 2026"
---

<style>
:root {
  --color-foreground: #1a1a2e;
  --color-highlight: #005f8a;
  --color-dimmed: #4a6a7a;
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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 {
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  color: #00b4d8;
  padding: 0.15em 0.4em;
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a {
  color: var(--color-highlight);
}
</style>

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# 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

---

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![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`?