[webcomponents] Custom Elements Spec

Based on the hallway conversations at the F2F, here are some notes for
the upcoming Custom Elements spec.

Custom tags vs. "is" attribute
- "is" attribute is awkward, overly verbose
- custom tags introduce local semantics
- generally viewed as a rabbit-hole discussion in WebApps scope
- Tantek (tantek) suggested we work this out in HTML WG
- perhaps start with something as simple as reserving "x-" prefix on
HTML tags for local semantics.

Instantiation and running script
- both Microsoft and Mozilla folks wish to avoid running script when
instantiating elements, which is a valid concern (mutation events
redux)
- instantiation of the element must set up the prototype chain
properly, since ES5 does not allow prototype swizzling
- Tony (tross) is worried that even if handled asynchronously, the
performance characteristics of running script when parsing HTML should
be carefully considered
- Jonas (sicking) reiterated that it is _critical_ that the custom
element's behavior is strongly bound to the lifetime of its element

Random ideas from various people:
- Minimal custom elements: spec building the prototype chain in
parser, spec template tag. Given these, the rest of the spec can be
implemented in JS.
- Start writing the spec with element instantiation, evaluate
performance issues and tweak until awesome.
- Ship Shadow DOM, reserve "x-" prefix, and let the Web devs start
using new stuff. Study what comes back and see what else needs to be
done.

:DG<

Received on Tuesday, 1 May 2012 23:43:08 UTC