Browser Version or Bug Detection

Question

I've recently seen some information about avoiding coding to specific browsers an instead using feature/bug detection. It seems that John Resig, the creator of jQuery is a big fan of feature/bug detection (he has an excellent talk that includes a discussion of this on YUI Theater). I'm curious if people are finding that this approach makes sense in practice? What if the bug no longer exists in the current version of the browser (It's an IE6 problem but not 7 or 8)?

Answer 1

Object detection's greatest strength is that you only use the objects and features that are available to you by the client's browser. In other words given the following code:

if (document.getFoo) {
    // always put getFoo in here
} else {
    // browsers who don't support getFoo go here
}

allows you to cleanly separate out the browsers without naming names. The reason this is cool is because as long as a browser supports getFoo you don't have to worry which one it is. This means that you may actually support browsers you have never heard of. If you target user agent strings find the browser then you only can support the browsers you know.

Also if a browser that previously did not support getFoo gets with the program and releases a new version that does, you don't have to change your code at all to allow the new browser to take advantage of the better code.

Answer 2

Well, if it is a problem in IE 6, but not IE 7 or IE 8 then the feature/bug detection mechanism will mark it as not a problem and use the appropriate functions.

It makes sense in practice, browser sniffing causes many issues, what if you don't update your signatures in time for some new browser that is released? You are now locking out potential customers, and visitors because you believe that their browser is unable to support something that indeed it can.

So yes, it makes sense, and your second question is moot because of the fact that it does the detection in the first place, if it is no longer a bug everything will work as expected without the work around that is in place if the bug was there!

Answer 3

Version and User Agent parsing remind me of stereotyping or racial profiling. Object detection is the way to go in my opinion. The book jQuery in Action does a good job of pointing out the fine details of why.

Answer 4

What if the bug no longer exists in the current version of the browser (It's an IE6 problem but not 7 or 8)?

That's the whole point of feature/bug detection. If the browser updates its features or fixes a bug, then the feature/bug detecting code is already up to date. If you're doing browser sniffing on the other hand, you have to change your code every time the capabilities of a browser changes.