function warnuser()
{
    return "Don't refresh the page.";
}

window.onbeforeunload = warnuser;

If the user refreshes the page and the user clicks 'leave this page' on confirmation box, i want to call a javascript function , otherwise not! I am confused about how to do that. Thank you

function warnuser()
{
    return "Don't refresh the page.";
}

window.onbeforeunload = warnuser;

If the user refreshes the page and the user clicks 'leave this page' on confirmation box, i want to call a javascript function , otherwise not! I am confused about how to do that. Thank you

• javascript
• onbeforeunload

• 3 If refreshing the page causes a problem, you should probably be focusing your efforts on making it not be a problem instead of preventing people from doing it in the first place. – Quentin Commented Jul 1, 2012 at 21:55
• I agree with @Quentin, you probably need to be conforming to the "Post Redirect Get" paradigm. – Travis J Commented Jul 1, 2012 at 21:56
• 1 @jezternz - There is always a way! :) But going down the hack path will forever dominate your codebase :P – Travis J Commented Jul 1, 2012 at 21:57
• I need to do that...m half the way in finishing this....just want to know how can i know whether user clicked on 'Stay on this page' or 'leave this page' and perform some action accordingly. – Rajat Commented Jul 1, 2012 at 22:09

2 Answers 2

You need to intercept the F5 key press and setup the onbeforeunload handler only in that case:

document.addEventListener('keydown', function(e) {
    if(e.which == 116) {
        window.onbeforeunload = function() {
            window.onbeforeunload = null;
            return "Do you really want to refresh the page?";
        }
    }
}, false);

Demo: http://jsfiddle/ejDrq/

Note that this does not work if the user clicks the Refresh button. It is impossible to intercept this.

If you have control of the server side which is hosting the page then you can handle this logically with a semaphore (wiki:semaphore). Basically it is a spinning lock which would be implemented in their server side session. Resetting the page state if they have entered and not exited in a safe manner. Naturally, as with all spinning locks, there would have to be a safe state to clear the lock out.