How can I stop the browser back button using JavaScript?

Question

I am doing an online quiz application in PHP. I want to restrict the user from going back in an exam.

I have tried the following script, but it stops my timer.

Answer 1

I believe the perfect yet solution is actually pretty straightforward, which I used for many years now.

It's basically assigning the window's "onbeforeunload" event along with the ongoing document 'mouseenter' / 'mouseleave' events so the alert only triggers when clicks are outside the document scope (which then could be either the back or forward button of the browser)

$(document).on('mouseenter', function(e) { 
        window.onbeforeunload = null; 
    }
);

$(document).on('mouseleave', function(e) { 
        window.onbeforeunload = function() { return "You work will be lost."; };
    }
);