Question

Trying to figure out how to make a modal pop up on browser window exit. I know how to do an alert box, but I want to have users answer a questionnaire on exit, instead of a basic “are you sure you want to leave” alert box.

Answer 1

window.onbeforeunload = function () {
  return 'Your content has not been properly saved yet!';
};

This will make the browser display a confirmation box like this one:

As you can see, the string returned by the function is shown in the box.