We all know how good Firefox is and if something works in FF and doesn't work in other browsers, we generally blame the others for not being as good. Recently I have started to discover a downside of using FF. I came across a few situations where FF was too lenient and I could realize my mistake only upon (accidently) checking the code in CHROME.

Let me give a few examples where FF covers your mistakes before I tell you what I understood from it

1) Check out this example. If a certain element say 'A' is placed inside another element 'B' then FF considers the parent-child relationship of A and B without giving a damn about whether its a valid HTML markup or not.

So if I write some text directly inside a table tag, omitting the and tags it will blow up in any browser - even FF and the markup will obviously not validate. But what if its an hidden input field. You won't realize that its wrong unless you alert the value of the the hidden field by using one of jquery's DOM traversing mothods.. something like,

    $("#buttonInsideTD").click(function(){
        $(this).parent().parent().siblings().filter(':input').val();
    });

Please correct me if I am wrong, but logically its not valid markup... because input cannot be a valid child of table. It fails the W3C validator (which says -- document type does not allow element "input" here) and even eclipse throws those annoying yellow coloured warnings .. But it makes no difference to FF.

2) Ever tried parsing xml using jquery's $.find method ? FireFox parses it beautifully while Chrome and the others refuse to do it. I once came across a message board where some one was cribbing of $.find not working in chrome on an xml string. Infact I had come there in search of exactly the same thing. Some briliant guy had answered it by asking a counter question - why should a browser parse xml if its supposed to understand only html? Sounds right!  But FF parses it and without letting you know even one bit that what you are doing is wrong. (The solution to make it work is by writing a separate function that makes the xml suitable for parsing .. but that would be a topic for another blog post)

3) Firefox doesnt have any problem with the following mark up

    <a href=""><li></li></a>

But again, its wrong as per the standards.

So what I can understand from these examples is that Firefox treats html like xml and doesnt care if html rules are obeyed or not. If there are incorrectly coded elements in your document and the final result doesn't show up in the browser, they will pass as valid html and can only be detected if the source is tested for compatibility with standards or some dom methods are used on them and that too if checked in some other browser. (I am sure there is more to it than just this and I might be wrong as well. So any corrections are welcome.. )

So from now on its going to be simultaneous development and testing on both Firefox and chrome. But Firefox still remains my default browser for the firebug, the echofon, the frequent updates and every thing that makes Firefox exemplify the true open source spirit.