javascript - How to pop up an alert box when the browser's refresh button is clicked?

Question

If the user refreshes the page in question it will add another record to the database, so I want to warn the user through an alert box if they really want to refresh the page and if they click ok then the page should be refreshed otherwise if they click cancel it won't be.

How to make this type of alert box appear when the browser's refresh button is clicked in a way that is cross browser compatible?

Answer 1

You can do it like this:

window.onbeforeunload = function() {
  return "Data will be lost if you leave the page, are you sure?";
};

This would show a prompt to the user allowing them to cancel. It's not refresh specific, but for your purposes (like editing a question on SO) that doesn't seem to matter, it's loss of info no matter where you're leaving to.