[whatwg] Normalization of user selections

Aryeh Gregor Simetrical+w3c at gmail.com
Tue Jun 28 10:38:34 PDT 2011

On Fri, Jun 17, 2011 at 1:40 PM, Aryeh Gregor <AryehGregor at gmail.com> wrote:
> However, I'd still like to normalize author-set selections somewhat.
> At a minimum, for instance, we could guarantee that a selection's
> boundary point is always in a Text or Element node that descends from
> a Document.  That would be a big simplification by itself.  Does
> anyone object to that?

I've updated the spec to require this:


The boundary points of a selection's range must now always be a Text
or Element node that descends from a Document.  Trying to call
collapse(), extend(), selectAllChildren(), or addRange() in a way that
would make a boundary point not a Text or Element node will throw
INVALID_NODE_TYPE_ERR, and trying to make it a node that doesn't
descend from a Document will throw INVALID_MODIFICATION_ERR.  I'll add
more specific constraints on user-created selections later.  Does
anyone think this is a bad approach?  If so, feedback would be

One problem arose when I was doing this: what happens if the user gets
a range with getRangeAt() and then alters it directly?  In WebKit and
Opera, getRangeAt() returns a copy, so this is no problem, but in IE
and Gecko (and per current spec) it returns a reference.  The simplest
solution would just be to change the spec to match WebKit and Opera
here, so getRangeAt() returns a copy of the range and addRange() adds
a copy of the range.  The only downside I can see is it's more
complicated to alter a multi-range selection -- you'd have to remove
and re-add a range to change it.  But this doesn't seem like a big
deal.  Any objections if I change the spec to make these methods do

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