How to Efficiently Capture URL Changes in Greasemonkey Scripts Using MutationObservers?

Capturing URL Changes in Greasemonkey Scripts

In a Greasemonkey script, monitoring URL modifications using events is often necessary. However, polling or timeout methods may not be ideal. Here's a solution that employs MutationObservers to detect and handle URL changes seamlessly.

To implement this approach, follow these steps:

1. Initialize DOM Reference Variables:

   • Initialize a variable to hold the original URL: var oldHref = document.location.href;
   • Select the body element for MutationObserver monitoring: var bodyList = document.querySelector('body');

2. Create a MutationObserver:

   • Instantiate a MutationObserver with a callback function that triggers when the URL changes: var observer = new MutationObserver(function(mutations) { ... });

3. Configure MutationObserver Options:

   • Configure the observer to monitor child changes and subtree changes: var config = { childList: true, subtree: true };

4. Add Observer to DOM:

   • Start observing the body element for changes: observer.observe(bodyList, config);

5. Handle URL Changes in Callback:

   • Within the observer callback, check for URL changes and perform necessary actions: if (oldHref != document.location.href) { ... }

This solution leverages MutationObservers, which provide an efficient way to monitor DOM changes, including those resulting from URL modifications. It avoids polling or timeout methods, ensuring real-time detection of URL changes and access to the DOM of the document pointing to the modified URL.

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