Should FF Error Console "Warnings" be taken seriously if page is not "broken"?

Question

I'm got a list of errors that was generated from the Error Console in FF. I've done some reading here on exactly what this tool is and how important/priority these errors are as far as "bug fixes". The css is rendering fine in FF on these particular pages as well as in Safari, Chrome, IE 7/8/9. I've gone to several websites (even stackoverflow.com) and it appears that ALL websites have a Long list of 'warnings' resulting in the Error Console. I've quoted someone who shared my reaction:

"Great info on the ERROR CONSOLE however information for the its own sake is useless unless there is information on how to repair* the specific errors on my LONG LIST. Maybe someone has an answer*." ~ Jullian

*bold added.

I'm wondering how seriously I should consider this list if the pages are not "broken", especially since long "warning" lists are common among all websites. Anybody?

Answer 1

In general, if warnings are serious enough that action is required, they would be errors.

Warnings are usually things that the browser thinks might be a mistake but isn't sure. It's up to you to make a judgement call on whether or not the warnings should be fixed.

If the warnings are JavaScript related, it would probably be a good idea to fix them. CSS warnings are usually less serious. CSS has so many browser specific quirks and, sometimes, hacks required to get things working that the browser can have a hard time knowing what should be considered "bad". It's not uncommon for lots of CSS warnings to appear that can be ignored.

Regardless, you might want to at least look at the warnings before dismissing them. They might reveal something you didn't think of.

Answer 2

The console is used to gather page data and debugging. These messages can be used to diagnose problems. If you are not experiencing any problems, then you are not required to worry. Some day you may need it though, and thats why its there.

Answer 3

The answer depends very much on what the errors are that you're getting.

In the case of StackOverflow, virtually all the "errors" being reported are due to their use of CSS hacks to target specific browsers (mainly different versions of IE).

For example, in SO's stylesheet, the following throws a couple of errors:

.wmd-preview pre>code:first-child{max-height:600px\9;display:block\9;}

The \9 syntax is invalid CSS, and Firefox rightfully complains about it. But this syntax is a deliberate CSS hack, which targets IE8 and earlier (See here for more info). The intention here is that all browsers other than IE8 and earlier would see that it is an error and drop the style.

Likewise, they are using the filter style, which is only supported by IE. Again, this will throw errors in Firefox, but they're expecting it to because they know that Firefox doesn't support this style.

Therefore in this context, the error is indeed expected and the developer would not worry about it appearing in Firefox's error console.

Looking through the error console after loading SO, this applies to virtually all the 'errors' they've got. They will know about and be expecting all of these errors, and they can thus be safely ignored.

If you're also getting your errors as a result of deliberate hacks, then feel free to ignore them when they show up in the error console.

However, if you're getting errors that you're not expecting, then you most certainly do want to pay attention to it. If there is an error in the console, then the one thing you can be certain of is that you have a broken bit of CSS. Unless it's a deliberate hack, then this will result in your stylesheets not rendering the site as you intended. The glitch may be very subtle, but it will be there.