URLs umleiten und umschreiben

Welcome! In this lesson, we'll learn how browser extensions can change where network requests go or how their URLs look.

• Redirecting sends a request to a completely different URL.
• Rewriting modifies parts of the original URL before it's processed.

Both are powerful tools for controlling web traffic using the `declarativeNetRequest` API.

Modifying URLs can serve many useful purposes:

• Enforce HTTPS: Automatically upgrade insecure HTTP connections.
• Fix broken links: Redirect old URLs to new ones.
• Clean up URLs: Remove unnecessary tracking parameters.
• Block unwanted content: Redirect specific requests to an empty page.

It helps improve security, privacy, and user experience.

To redirect a network request, we use the `redirect` action type in our `declarativeNetRequest` rules. This action specifies a new URL or a pattern to generate one.

Here's a basic structure for a redirect rule:

Let's say you want to redirect all requests to an old blog post URL to a new one. This rule tells the browser: 'If you see a request for old-blog.html, send it to new-blog-post.html instead.'

A common use case is to ensure secure connections. You can redirect all HTTP requests for a specific domain to their HTTPS equivalent. This enhances user security by encrypting data.

This rule redirects any HTTP request for example.com to its HTTPS version.

Sometimes you don't want to redirect to a fixed URL, but rather modify parts of the original URL. This is where regexSubstitution comes in. It uses regular expressions to match and replace parts of the URL.

The matched parts from the regexFilter in the condition can be referenced in the substitution string using backreferences like \1, \2, etc.

Imagine you have old URLs like /users/123 and want them to become /profile/123. You can use regexSubstitution to capture the ID and rewrite the path.

This rule captures the number after /users/ and reuses it in the /profile/ path.

regexSubstitution is great for cleaning up query parameters. You might want to remove a specific tracking parameter, like utm_source, from URLs to improve privacy or simplify sharing.

This rule matches URLs with ?utm_source=... and removes that parameter, keeping everything else.

Remember, `urlFilter` uses match patterns, which are simpler for basic matches. `regexFilter` requires full regular expressions and is used when you need to capture parts of the URL for `regexSubstitution`.

• Match Patterns: Wildcards like *, specific schemes/hosts.
• Regular Expressions: Powerful pattern matching with groups () and special characters.

Choose the right tool for the job!

Consider a rule designed to redirect all requests from http://insecure.com to https://secure.com. Which `redirect` action type is best suited for this goal?

Great job! You've learned how to powerfully control network requests:

• Redirects: Send requests to entirely new URLs using `redirect` with a `url`.
• Rewrites: Modify parts of URLs using `redirect` with `transform` or `regexSubstitution`.
• HTTPS enforcement: A practical use of `transform` to upgrade connections.
• URL cleaning: Use `regexSubstitution` to remove or change parameters.

These techniques allow you to enhance security, fix issues, and customize user browsing experiences.