How to show the “Are you sure you want to navigate away from this page?” when changes committed?

Question

Here in stackoverflow, if you started to make changes then you attempt to navigate away from the page, a javascript confirm button shows up and asks: \"Are you sure you want

Answer 1

What you want to use is the onunload event in JavaScript.

Here is an example: http://www.w3schools.com/jsref/event_onunload.asp