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

You can determine if a tab or window is active by attaching a blur / focus event listener to window.

in jQuery it would be

$(window).focus(function() {
    //do something
});

$(window).blur(function() {
    //do something
});

quoted from this SO answer: https://stackoverflow.com/a/1760268/680578