On 19/10/11 7:20 AM, Yehuda Katz wrote:
I agree entirely.
I have asked a number of practitioner friends about this scenario:
<div id="parent">
<p id="child"><span id="inline">Content</span></p>
</div>
document.getElementById("child").querySelectorAll("div span"); //
returns #inline
In 100% of cases, people consider this behavior *broken*. Not just
"interesting, I wouldn't have expected that", but "who came up with
that!?". In all cases involving JavaScript practitioners, people
expect querySelectorAll to operate on the element as though the
element was the root of a new document, and where combinators are
relative to the element.
It matches the definition of CSS selectors, so I don't think it can be
called broken. For this case, node.querySelectorAll("div span") finds
all span's (in document order) which are contained within the invoking
node and checks that they match the selector expression, in this case
simply checking they are a descendant of a div.
The new definition being promoted is:
- start at the containing node
- find all descendant div's
- for every div, find all descendant span's.
- with the list of span's, remove duplicates and place in document-order
Once you understand the proper definition it is hard to see this new
definition as more logical.
To me, the problem here is some (not all) Javascript practitioners not
learning the proper definition of CSS selectors.
We already knew this was true since all JavaScript libraries that
implement selectors implemented them in this way.
To me, this indicates that there's no problem here. If you want to use
an alternative definition of selectors then you use a JS lib that
supports them. If you want to use the DOM API then you learn how CSS
selectors work.
I don't see JS libs ever calling the browsers querySelectorAll (or even
a new findAll) without parsing the selector string first because:
- JS libs support selectors that haven't been implemented on all browsers
- JS libs support selectors that are never going to be part of the standard
Since JS libs will always parse selector strings and call qSA, etc as
appropriate, I can't see much benefit in creating DOM methods that
accept non-standard selector strings.
Sean
