Dear Web Apps WG,
I've reviewed the Selectors API [1], and have one comment:
The Interoperability Considerations section states that in certain
cases "such implementations could return different results from those
that do support them". While this is a non-normative section, just
referring to "different results" seems a bit too vague and is not
really helpful for applications relying on the specification. Even
more worrying, after reading the rest of the specification and the
underlying Selectors specification [2] I can still not tell what the
intended behavior is. The Selectors specification introduces Profiles,
which indicate which selectors are supported ("accepted") by a
specification using Selectors, but it neither introduces a similar
concept for implementations, nor does it seem to specify the behavior
resulting from the use of selectors that are not supported by a
specification or an implementation.
I would expect the specification to prescribe
- either that the implementation raises an exception when given a
selector that it doesn't support,
- or that the implementation return null (for querySelector) or an
empty list (for querySelectorAll) when given a selector that it
doesn't support.
Best regards,
Norbert Lindenberg
[1] http://www.w3.org/TR/2008/WD-selectors-api-20081114/
[2] http://www.w3.org/TR/2005/WD-css3-selectors-20051215/
