LearnJS Progress Tracker is a Chrome extension developed by Nikromes. It is a free program that falls under the category of Browsers, specifically Add-ons & Tools. With this extension, users can track their progress in learning JavaScript on the LearnJS ru website.

After installing the extension, users will have the ability to mark the pages they have completed with one of two options: "mastered material" or "material to review." These marked pages will be highlighted with different colors, making it easy for users to visualize their progress.

Additionally, on the main page of the website, users can see how far they have advanced in their learning journey. The extension is designed to work with both light and dark themes, providing a seamless experience for users.

It's important to note that if the extension is uninstalled, all progress information will be lost. Overall, LearnJS Progress Tracker is a useful tool for individuals learning JavaScript on the LearnJS ru platform, allowing them to keep track of their progress and stay motivated.