How to debug javascript? [duplicate]

Answer 1

Firebug for firefox is okay. The console for safari and chrome, IMO, is better. In either case, right click the page, hit "inspect element," and click the "console" tab in the pane that pops up. Now you'll see any errors and warnings generated by the page.

If you really want to debug the scripts you can click on the "Scripts" tab and either pause execution immediately or set a break point. Then, you can step through the execution of the script line by line, inspecting the call stack and watch list as you go.

Answer 2

There's FireBug, but it only works for Firefox.

EDIT: Doh, you already mentioned this in your question.

Answer 3

Firefox doesn't popup error messages or put them in the status bar (like IE). You have to open the Error Console to see the errors.

Firefox puts Javascript errors in the Error Console, but also HTML and CSS errors and warnings.

As to what might not work in the code, there are plenty of things that are IE specific and won't work in any other browser. Also there is a big difference between IE in quirks mode and IE in standards compliant mode. Put a proper doctype in the page so that it's rendered in standards compliant mode, which will make IE more like other browsers, and some IE-specific quirks are removed. This might cause your old script to stop working, in which case you know that it's likely that it's some IE-specific feature that causes the problem.