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

For Restrict Browser back event

window.history.pushState(null, "", window.location.href);
window.onpopstate = function () {
    window.history.pushState(null, "", window.location.href);
};