JavaScript debugging in FireFox

In Internet explorer, when there's a JavaScript error, I get a little popup that tells me so. This doesn't happen in FireFox 3. How do I enable this in FF?

I realize this isn't a programming question per se (please don't close this question; forgive me!), but I'm trying to debug some JavaScript and it'd be really nice to see these messages.

I have FireBug enabled if that makes a difference. 开发者_运维百科(Nothing comes up in Firebug either.)

Although you have Firebug, you probably don't have it correctly enabled. Right click the bug icon and select Enable all panels and On for all websites.

You may also try the Error console which lies under the Tools menu.

Under the "Tools" Menu and select "Error Console" - hope that helps

perhaps your code does something that doesn't throw an error in Firefox (like string[indexing])

FireBug won't pop up when there's an error, either. Instead, it'll show up in the Console tab assuming it is enabled in the way described by Miguel earlier.