Multiple-selector doesn't return elements in document order

[atifaziz]

http://api.jquery.com/multiple-selector/ states that for a multiple-selector "The order of the DOM elements in the returned jQuery object ... will be in document order."

Fizzler doesn't respect this order, instead returning all the matches for each selector in turn and not in document order.

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Originally reported on Google Code with ID 43

Reported by HighTechRider on 2011-01-16 20:48:12

[atifaziz]

Is this behavior defined by CSS standard, or is it just a jQuery feature?

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Reported by edin.dazdarevic on 2011-01-24 21:29:12

[atifaziz]

Whilst jQuery does define this, the CSS spec does not appear to: CSS3 "A comma-separated list of selectors represents the union of all elements selected by each of the individual selectors in the list."

Since jQuery and Fizzler can be used to manipulate (and not just display) documents it's arguably far more important that they each define an order for how that union happens.

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Reported by HighTechRider on 2011-01-24 22:42:17

[atifaziz]

Fizzler intentionally does not return the results in document order because running a sort would end up buffering the results prior to yielding them. This was done to maintain deferred execution semantics as much as possible and make the caller pay for only the least necessary computation. For cases where document order is significant, it seemed reasonable to let the caller compose the results of QuerySelectorAll with OrderBy.

HtmlAgilityPack.HtmlNode has a StreamPosition property that can be used as the key to get the results sorted in document order. Unfortunately, earlier versions of HtmlAgilityPack also seemed to have an unreliable StreamPosition so that was another (though lesser) reason for delegating the decision to sort to the caller.

I am less concerned with jQuery. What Fizzler clearly violates is the querySelectorAll contract specified as part of the NodeSelector interface and which states:

The querySelectorAll() method on the NodeSelector interface must, when invoked, return a NodeList containing all of the matching Element nodes within the node’s subtrees, in document order.

One way forward I see is first have QuerySelectorAll return nodes in document order. This way, there are no surprises but it will be clearly returning buffered results (the inefficiency of which may in itself surprise others). Then supply a non-normative alternative (YieldQuerySelectorAll?) that does not guarantee document order but which streams out the results.

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Reported by @atifaziz on 2011-01-25 01:12:22

[atifaziz]

Reported by azizatif on 2011-01-25 01:12:33

• Status changed: Accepted