What Language Is Best For Tracking On-Site Behavior?

I'm new to writing code and want to build a platform that can track on-site behaviors on a website by a user. I am looking to track things like, time on page (even if they did not go to a second page on the site), what their mouse hovers over, what pages they went to, etc. I'm sure difficult to implement but conceptually nothing new.

What coding language would be best for that? I'm sure that is a loaded question when I mean best I mean: most scaleable (if that's a thing) and most flexible to work with other coding languages (if that is also a thing). I have a small amount of python knowledge if that means anything.

Thanks in advance to anyone with suggestions.

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TLDR: I want to build software to track what users do on a website, and allow this to be implemented by the website owner by pasting a small snippet code to their site (like Google Analytics). What is the best language for this?