A spider (also called a web crawler or bot) is an automated program that browses the internet to index web pages. These programs are often used by search engines like Google, Bing, or Yahoo to discover and update content in their search index.
Starting Point: The spider begins with a list of URLs to crawl.
Analysis: It fetches the HTML code of a webpage and analyzes its content, links, and metadata.
Following Links: It follows the links found on the page to discover new pages.
Storage: The collected data is sent to the search engine’s database for indexing.
Repetition: The process is repeated regularly to keep the index up to date.
Search engine optimization (SEO)
Price comparison websites
Web archiving (e.g., Wayback Machine)
Automated content analysis for AI models
Some websites use a robots.txt file to specify which areas can or cannot be crawled by a spider.
An Internationalized Resource Identifier (IRI) is an extended version of a Uniform Resource Identifier (URI) that supports Unicode characters beyond the ASCII character set. This allows non-Latin scripts (e.g., Chinese, Arabic, Cyrillic) and special characters to be used in web addresses and other identifiers.
A-Z
, 0-9
, -
, .
, _
), IRIs allow characters from the entire Unicode character set.https://de.wikipedia.org/wiki/Überblick
https://de.wikipedia.org/wiki/%C3%9Cberblick
Ü
is encoded as %C3%9C
)IRIs are defined in RFC 3987 and are supported in modern web technologies like HTML5, XML, and RDF.
IRIs make the internet more linguistically inclusive by allowing websites and resources to be referenced using non-Latin characters, improving accessibility worldwide.
A SUT (System Under Test) is the system or component being tested in a testing process. The term is commonly used in software development and quality assurance.
A typical testing process includes:
The Whoops PHP library is a powerful and user-friendly error handling tool for PHP applications. It provides clear and well-structured error pages, making it easier to debug and fix issues.
✅ Beautiful, interactive error pages
✅ Detailed stack traces with code previews
✅ Easy integration into existing PHP projects
✅ Support for various frameworks (Laravel, Symfony, Slim, etc.)
✅ Customizable with custom handlers and loggers
You can install Whoops using Composer:
composer require filp/whoops
Here's a simple example of how to enable Whoops in your PHP project:
require 'vendor/autoload.php';
use Whoops\Run;
use Whoops\Handler\PrettyPageHandler;
$whoops = new Run();
$whoops->pushHandler(new PrettyPageHandler());
$whoops->register();
// Trigger an error (e.g., calling an undefined variable)
echo $undefinedVariable;
If an error occurs, Whoops will display a clear and visually appealing debug page.
You can extend Whoops by adding custom error handling, for example:
use Whoops\Handler\CallbackHandler;
$whoops->pushHandler(new CallbackHandler(function ($exception, $inspector, $run) {
error_log($exception->getMessage());
}));
This version logs errors to a file instead of displaying them.
Whoops is mainly used in development environments to quickly detect and fix errors. However, in production environments, it should be disabled or replaced with a custom error page.
TortoiseGit is a graphical user interface (GUI) for Git, specifically designed for Windows. It is an extension for Windows Explorer, allowing users to manage Git repositories directly via the context menu.
✅ Windows Explorer Integration → No separate tool needed; everything is accessible via the right-click menu
✅ User-Friendly → Ideal for those unfamiliar with the Git command line
✅ Visual Support → Changes, diffs, logs, and branches are displayed graphically
✅ Push, Pull, Commit & Merge → Perform standard Git operations via the interface
✅ Support for Multiple Repositories → Manage multiple projects simultaneously
TortoiseGit requires a Git installation (e.g., Git for Windows) to function.
➡ Download & More Info: https://tortoisegit.org/
The Fetch API is a modern JavaScript interface for retrieving resources over the network, such as making HTTP requests to an API or loading data from a server. It largely replaces the older XMLHttpRequest
method and provides a simpler, more flexible, and more powerful way to handle network requests.
fetch('https://jsonplaceholder.typicode.com/posts/1')
.then(response => response.json()) // Convert response to JSON
.then(data => console.log(data)) // Log the data
.catch(error => console.error('Error:', error)); // Handle errors
Making a POST Request
fetch('https://jsonplaceholder.typicode.com/posts', {
method: 'POST',
headers: {
'Content-Type': 'application/json'
},
body: JSON.stringify({ title: 'New Post', body: 'Post content', userId: 1 })
})
.then(response => response.json())
.then(data => console.log(data))
.catch(error => console.error('Error:', error));
✅ Simpler syntax compared to XMLHttpRequest
✅ Supports async/await
for better readability
✅ Flexible request and response handling
✅ Better error management using Promises
The Fetch API is now supported in all modern browsers and is an essential technique for web development.
A Single Page Application (SPA) is a web application that runs entirely within a single HTML page. Instead of reloading the entire page for each interaction, it dynamically updates the content using JavaScript, providing a smooth, app-like user experience.
✅ Faster interactions after the initial load
✅ Improved user experience (no full page reloads)
✅ Offline functionality possible via Service Workers
❌ Initial load time can be slow (large JavaScript bundle)
❌ SEO challenges (since content is often loaded dynamically)
❌ More complex implementation, especially for security and routing
Popular frameworks for SPAs include React, Angular, and Vue.js.
Puppet is an open-source configuration management tool used to automate IT infrastructure. It helps provision, configure, and manage servers and software automatically. Puppet is widely used in DevOps and cloud environments.
✅ Declarative Language: Infrastructure is described using a domain-specific language (DSL).
✅ Agent-Master Architecture: A central Puppet server distributes configurations to clients (agents).
✅ Idempotency: Changes are only applied if necessary.
✅ Cross-Platform Support: Works on Linux, Windows, macOS, and cloud environments.
✅ Modularity: Large community with many prebuilt modules.
A Puppet manifest (.pp
file) might look like this:
package { 'nginx':
ensure => installed,
}
service { 'nginx':
ensure => running,
enable => true,
require => Package['nginx'],
}
file { '/var/www/html/index.html':
ensure => file,
content => '<h1>Hello, Puppet!</h1>',
require => Service['nginx'],
}
🔹 This Puppet script ensures that Nginx is installed, running, enabled on startup, and serves a simple HTML page.
1️⃣ Write a manifest (.pp
files) defining the desired configurations.
2️⃣ Puppet Master sends configurations to Puppet Agents (servers/clients).
3️⃣ Puppet Agent checks system state and applies only necessary changes.
Puppet is widely used in large IT infrastructures to maintain consistency and efficiency.
Jest is a JavaScript testing framework developed by Meta (Facebook). It is mainly used for testing JavaScript and TypeScript applications, especially React applications, but it also works well for Node.js backends.
// sum.js
function sum(a, b) {
return a + b;
}
module.exports = sum;
// sum.test.js
const sum = require('./sum');
test('addiert 1 + 2 und ergibt 3', () => {
expect(sum(1, 2)).toBe(3);
});
o run the test, use:
jest
Or, if installed locally in a project:
npx jest
CSS Media Queries are a technique in CSS that allows a webpage layout to adapt to different screen sizes, resolutions, and device types. They are a core feature of Responsive Web Design.
@media (condition) {
/* CSS rules that apply only under this condition */
}
1. Adjusting for different screen widths:
/* For screens with a maximum width of 600px (e.g., smartphones) */
@media (max-width: 600px) {
body {
background-color: lightblue;
}
}
2. Detecting landscape vs. portrait orientation:
@media (orientation: landscape) {
body {
background-color: lightgreen;
}
}
3. Styling for print output:
@media print {
body {
font-size: 12pt;
color: black;
background: none;
}
}
✅ Mobile-first design: Optimizing websites for small screens first and then expanding for larger screens.
✅ Dark mode: Adjusting styles based on user preference (prefers-color-scheme
).
✅ Retina displays: Using high-resolution images or specific styles for high pixel density screens (min-resolution: 2dppx
).