To prevent a JS timer from freezing in a Chrome tab?

Question

JavaScript

I use an intervalset of 0.5 seconds. I fold and make a stopwatch in the browser.
After 3.5 hours I switch to the stopwatch tab, I see: 1.5 hours have passed ..
How to make the script not freeze?
How does VK do it for example?

Answer 1

Do not count via setInteval. Create a constant with the start date of the timer, and every N-times calculate the amount of time from the initial constant up to the current moment.

Answer 2

webworkers can be used