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Disabling alerts stops JavaScript execution in Firefox

Today I learned about interesting issue with newer versions of Firefox (I use FF7). It has a nice web developer-friendly feature to disable alerts. This is really useful when you place alert() by mistake in some loop and you can't get out because as soon as you click OK, you get another one.

New Firefox has a checkbox to disable future alerts. And this is great. So, what's the problem? Once you disable alerts, and javascript code is executed that would display it, it does not keep running, but rather throws an exception. This does not look like correct behavior to me.

Imagine a web application that alerts user about something and then keeps running to finish the job. If user disabled alerts because he was in a hurry and clicked fast on different message boxes, the script would not keep going but stop. And there is no way to revert that short of reloading the page (yikes!).

I found a workaround, I created a function called tryalert that wraps the alert in try..catch block. It looks like this:

function tryalert(message)
    try { alert(message); } catch(e) {}

This is a fine workaround. Now instead of alert() I call tryalert() and although the alert is not displayed anymore, the code keeps going as if user has been alerted.

The problem is introducing tryalert to ALL applications I've written so far. It's impossible. I hope Firefox team changes this.

Milan Babuškov, 2011-12-01
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