Should TreeWalker be expanded to support shadow roots in support of the selection API?

[keithamus]

(from w3c/selection-api#164)

WCCG had their spring F2F in which this was discussed. Present members of WCCG identified an action item to raise this issue. You can read the full notes of the discussion (WCCG had their spring F2F) in which this was discussed, heading entitled "Selection API". I won't be quoting the notes for brevity.

TreeWalker was discussed as a mechanism to walk the DOM to gather textcontent of the currently selected nodes, but it was pointed out that TreeWalker does not iterate over shadow roots.

This issue is to discuss the expansion of TreeWalker to support shadow roots, perhaps using a shadowroots: option to provide contained shadow roots?

Refs w3c/selection-api#161

[annevk]

I personally consider NodeIterator and TreeWalker to be deprecated. We didn't go through the exercise of giving them useful constructors for instance. Based on that I'd be inclined not to update them, but if they have sudden surge in popularity we could revisit that I suppose.

[smaug----]

Do we have any use counters for the APIs? (Firefox doesn't have)

[zcorpan]

We have httparchive! Total number of pages in the dataset is 12,808,711.

• 979,195 = 7,64% of pages use createNodeIterator()
• 2,708,575 = 21.15% of pages use createTreeWalker()

https://docs.google.com/spreadsheets/d/1AJRajLjk7SvKTjuZMUOsYHobgFVThA5BN-Na2qNoTKA/edit?usp=sharing

From looking at the first bunch it looks like adsense appears pretty frequently.

Reducing to first-party resources, we get:

• 208,801 = 1.63% of pages with first-party createTreeWalker()
• 74,335 = 0.58% of pages with first-party createNodeIterator()

https://docs.google.com/spreadsheets/d/1IKPHOVHugHS0pwHvNj6TbpSiIBZM18KpUGI0nLvKmeY/edit?usp=sharing

https://almanac.httparchive.org/en/2022/javascript#fig-45 says last year 0.39% of pages use shadow dom. Assuming an even distribution the pages using both shadow DOM and first-party createTreeWalker() would be 0.009% of pages; shadow DOM and first-party createNodeIterator() 0.002% of pages.