[whatwg] getElementsByClassName()

Ian Hickson ian at hixie.ch
Mon Oct 23 13:03:03 PDT 2006

On Sun, 22 Oct 2006, Anne van Kesteren wrote:
> On Sat, 21 Oct 2006 09:36:37 +0200, Ian Hickson <ian at hixie.ch> wrote:
> > This omnibus edition of your WHATWG mail includes replies to 50 or so
> > separate e-mails about getElementsByClassName(). Thanks to everyone for
> > their comment on this issue.
> So what's the use case over matchAll(".foo.bar.baz") ..?

None; it's just a complementary method in line with getElementById(), 
getElementsByTagName(), and getElementsByName() methods. (Also, it returns 
a live list, instead of a static list.)

On Mon, 23 Oct 2006, James Graham wrote:
> I guess the question is "why bother with getElementByClassName if a full 
> getElementByCSSSelector-type method is available"?. Possible answers 
> would include speed and ease of use but I'm not sure either applies 
> here.

I think there's room for both. I don't have a strong opinion, though; if 
other people think we should not add getElementsByClassName() then please 
speak up.

On Mon, 23 Oct 2006, Dean Edwards wrote:
> This has been debated to death. People want this function. So I think we 
> should add it. The only arguments against are that there are potentially 
> better solutions, like matchAll/matchSingle. I don't think that is a 
> good enough reason to not include it. First, it is analogous to 
> getElementsByTagName. Second, alternatives are not currently 
> implemented.
> It is not uncommon for API's to provide more than one way to achieve the 
> same end. I don't see why the DOM should be any different. It is not 
> going to break anything and people want it -- so let's spec it. I 
> haven't heard a good argument against inclusion yet and we are on the 
> 87th comment in this thread.

I agree with Dean.

On Mon, 23 Oct 2006, Jonathan Worent wrote:
> There seems to be a question on how confusing a method would be for 
> developers. I went and asked 4 people I know that are just learning 
> Javascript for the first time. For two of them javascript is their first 
> programing language, the other two already know other languages.
> Given this markup:
> <p class="foo bar">Para 1</p>
> <p class="bar foo">Para 2</p>
> <p class="foo baz">Para 3</p>
> All expected that getElementsByClassName("foo bar"); would match "foo 
> bar" exactly in the class name and only return Para 1.
> When asked if they would prefer a comma separated list or an array, 
> there were mixed feelings. Three indicated a preference to a comma 
> separated list, the other said he would expect to pass an array. Given 
> this I would suggest not using a space delimited list.

Ok, that's a compelling argument. I've removed the string version. We're 
down to just the array form now. If people want to call the method with a 
single class, they have to use square brackets; if they want to call it 
with a space-separated list of classes, they have to use .split() or some 

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http://ln.hixie.ch/       U+263A                /,   _.. \   _\  ;`._ ,.
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