Javascript to detect if user changes tab

Question

I want to write a webpage for online quiz.Basic requirement i have is that, If the person taking quiz changes tab or opens new window even without minimizing browser, i.

Answer 1

Best native function hands down, no jQuery.

document.hasFocus

Check the pen, check what happens when you go to the link and back to the codepen tab.

https://codepen.io/damianocel/pen/Yxxzdj