Re: Improving DOM Traversal and DOM XPath

On Mon, Apr 25, 2011 at 11:31 AM, Jonas Sicking <jonas@sicking.cc> wrote:

> First off is document.createTreeWalker and
> document.createNodeIterator. They have the same signature which
> currently is:
>
> document.createX(root, whatToShow, filter, entityReferenceExpansion);
>
> Given that entity references are being removed, we should simply
> remove the last argument. Note that this is a backwards compatible
> change since additional arguments to any DOM function are just ignored
> in all browsers I think. Additionally, I see no reason to keep the
> 'filter' argument required as it's quite common to leave out.
>

FWIW, WebKit already has filter and entityReferenceExpansion as optional. I
expect there would be no opposition to making whatToShow optional as well.

We could even make the whatToShow argument optinal and default it to
> SHOW_ALL. Originally I was going to propose that we default it to
> SHOW_ELEMENTS as I had thought that that would be a common value,
> however it appears that SHOW_TEXT is as, if not more, commonly used.
> The downside to defaulting to SHOW_ALL is that people might use the
> default and then do filtering manually, which is slower than having
> the iterator/treewalker do the filtering.
>

I agree with everything here. I think SHOW_ALL is the default people would
expect.


> I'd like to give some DOM XPath a similar treatment. The following
> three functions could be simplified:
>
> XPathEvaluator.createExpression(expression, resolver);
> Here I think we can make the 'resolver' argument optional as
> namespaces are commonly not used on the web.
>
> XPathEvaluator.evaluate(expression, contextNode, resolver, type, result);
> We can make 'resolver', 'type' and 'result' optional. 'type' would
> default to ANY_TYPE(0) and the other two to null.
>
> XPathExpression.evaluate(contextNode, type, result);
> Here all but the first could be optional. The defaults would be the
> same as for XPathEvaluator.evaluate.
>

These are already all optional in WebKit. We could also make contextNode
optional by defaulting it to the document, no?


> I'd like to make these changes to firefox, but first I wanted to hear
> what people here think.


I support this. As it is, I believe the verbosity of these methods hurts
their adoption.


> I know we don't have editors for the relevant
> specs, but I think we can make an informal decision that these changes
> sound good if people think they are.
>
> / Jonas
>
>