Keep track of how much time is spent showing certain elements on the page

Question

So lets say we have 4 Divs (3 hidden, 1 visible), the user is able to toggle between them through javascript/jQuery.

I want to calculate time spent on each Div, and

Answer 1

Javascript console internally has a function called "console.time() and console.timeEnd() to do the same. Simple you can use them

console.time("List API");
setTimeout(()=> {
  console.timeEnd("List API");
},5000);

More details can be found here https://developer.mozilla.org/en-US/docs/Web/API/Console/time