I'm a person who comes from algorithm and data structures background (in c++, c, Python, Java and etc.) and my only experience in frontend is Processing and p5.js. How browsers integrate html, css and js? Do Javascript scripts generate a new .html file as page at certain framerate? How does it really work inside the browser? Or do most popular libraries like Angular make "syscalls" to the web browser to generate content?

Does using libraries like Angular etc. make generating new html "frame" documents somehow automated for dynamic pages?

I mean apart from all Javascript operations isn't the final displayed content a html file in the end?