Available at https://www.w3.org/2016/04/05-webapps-minutes.html or as text below.

Thanks to Jan Miksovsky for logistics, and in particular for scribing!

   [1]W3C

      [1] http://www.w3.org/

                               - DRAFT -

                     Web Components Teleconference

05 Apr 2016

   See also: [2]IRC log

      [2] http://www.w3.org/2016/04/05-webapps-irc

Attendees

   Present
          Jan Miksovsky, Domenic Denicola, Ryosuke Niwa, annevk,
          Dimitri Glazkov, Elliott Sprehn, Travis Leithead, Hayato
          Ito, dan, smaug

   Regrets
   Chair
          SV_MEETING_CHAIR

   Scribe
          Jan Miksovsky
     __________________________________________________________

   <Jan> Rniwa proposing we go through Domenic’s prioritized list
   of issues

   Domenic: let’s start with some easy ones
   ... seems like “restrict to secure contents” is not going to
   happen

   [no one objects]

   Domenic: I’ll note that in the thread

   annek: on attributeChangedCallback order, sounds like we can’t
   agree on an order

   rniwa: order is an interop issue

   annek: it’s going to take a long time before Gecko gets around
   to (preserving stable attribute order)

   elliott: there’s stuff to be sacrificed there
   ... what webkit does doesn’t end up with memory optimization
   ... we’re asking Gecko to reduce the effectiveness of their
   memory optimization
   ... Chrome and WebKit both agree

   elliott: there’s no interop here, so if we change it, nothing
   breaks
   ... MutationObserver is going to give you totally different
   order in diff browsers

   domenic: propose: keep the order that’s in the spec, general
   willingness to converge on determinism

   rniwa: ok, but I wouldn’t necessarily block the other browsers
   from implementing custom elements (by forcing determinism)

   elliott: doesn’t seem like a big enough win for Gecko

   <annevk> sorry dglazkov :-(

   Travis: try again

   <annevk> no jokes this time I guess

   <dglazkov> hangouts_queue.pop()

   (Travis joins video chat)

   rniwa: should we tackle “parse <slot> like <template>”?

   annek: it sounds like nobody is really interested in making
   parser changes
   ... i’m tempted to punt on the whole thing
   ... ideally a custom element could replace a <thead>, etc.,
   but...

   rniwa: I thikn that this would be really risky
   ... we’ve seen elements in the wild with a dash in their name,
   so changing this would be risky

   domenic: this would be nice, but probably not worth it
   ... nobody seems to be strongly advocating for it

   annek: this is probably okay as is

   travis: is there a good workaround?

   annke: you can always just use the DOM API to restrict your
   tree instead of the parser

   annek: but that’s a workaround
   ... or you could use custom elements for everything, reinvent
   all the elements

   elliott: that’s funny, html tables is missing column spans,
   that’s the only reason people use real tables
   ... the generalized solution we’d like to pursue is a meta tag
   that lets you opt into a more streamlined parser

   annek: an XML5 (?) parser

   elliott: we’ve spend so much time band-aiding this thing,
   that’s why we never went there

   annek: in general, that’s a fine plan

   travis: sounds like versioning to me

   annek: sounds more like strict mode

   elliott: the nature of such a thing is off topic

   annek: it is hard

   rniwa: alternative is to have an attribute to add an element to
   a slot

   domenic: certainly not v1, but any reason why that’s not a good
   idea

   rniwa: it kind of violates the fundamentals of the element

   annek: do you use display: contents on it, and then what does
   that mean? sounds like v2

   rniwa: an attribute way of adding a slot might be a v2 thing

   elliott: if this is popular, someone will write a library to
   (implement this feature), and that will be a signal to do this

   annek: let’s move to the top of the list, issue 308: should we
   use “display: contents"?
   ... I’m going to say “yes"
   ... … Gecko has an implementation of display: contents.

   rniwa: We haven’t done this yet, but our intention is to do so

   domenic: our position: reasonable semantics, main concern is
   that this adds a lot of implmentation
   ... would delay getting this into users’ hands

   travis: can someone restate the problem

   annek: can the <slot> element itself end up in the final
   layout/flat tree

   if it ends up there, you can style it; if not, you can’t do
   anything with it

   travis: iframes are sort of like super-slots, and they’re
   independently styleable
   ... but its background color doesn’t matter, because it gets
   replaced

   (as jan) I haven’t seend the need for this

   travis: maybe it shouldn’t have a particular representation

   annek: if blink ships with its current idea of not having it in
   the layout tree, ...

   and then changes some months later...

   elliott: this doesn’t really work, you could end up styling the
   slot by mistake
   ... you wouldn’t want to ship this
   ... any style applied to the slot is a no-op

   rniwa: we’re changing the behavior as we speak

   <Domenic_>
   [6]https://github.com/w3c/webcomponents/issues/308#issuecomment
   -204198578 outlines elliott's concerns in more detail

[6] https://github.com/w3c/webcomponents/issues/308#issuecomment-204198578

   rniwa: we also support computed styles on the slot
   ... principle is this: there are real use cases that display:
   none would be ignored
   ... that’s confusing
   ... every other kind of element is styleable

   elliott: it’s not clear to me that eveyrone has that
   expectation

   travis: but the slot will be there if you go exploring (in the
   DOM)

   elliott: yes, the slot is there, but you can’t put a border on
   it, or padding, or margin...
   ... assuming display: contents, you could put an inheritable
   property on it
   ... if I put :before and :after on the slot, do they apply?

   rniwa: this is an issue with display: contents in general

   elliott: I think display: contents is a confusing feature

   rniwa: if you want to object to that feature, you could do that
   with W3C

   elliott: I have
   ... coupling Shadow DOM to a feature that involves…

   rniwa: elliott and Tab (Atkins) both work for the same company,
   and should (be on the same page)

   elliott: there’s not concensus within Google that we need this
   feature
   ... there are a lot of edge cases that would be broken in v1

   annek: if we don’t do this in v1, we can’t add it later

   elliott: the only way to solve this in the future would be to
   introduce a new CSS property

   annek: there’s an element in the tree, and then it disappears
   from the tree, we don’t have anything else like that

   domenic: can you style the <meta> element?

   (someone) yes

   annek: it sounds like we add a style for style slot in the
   future that’s special, or do display: contents now

   elliott: it’s not clear that everyone’s agreed to the details
   of everything (Tab) is implying

   domenic: figuring out suitable semantics for everything is what
   we’re not excited about

   annek: if you do display: contents, you can have
   pseudo-elements

   <annevk>
   [7]http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!D
   OCTYPE%20html%3E%0A...%3Cstyle%3E%0Adiv%20%7B%20display%3Aconte
   nts%20%7D%0Adiv%3A%3Abefore%20%7B%20content%3A%22X%22%20%7D%0Ad
   iv%3A%3Aafter%20%7B%20content%3A%22X%22%20%7D%0A%20%3C%2Fstyle%
   3E%0A%3Cdiv%3Etest%3C%2Fdiv%3E

[7] http://software.hixie.ch/utilities/js/live-dom-viewer/?%3C!DOCTYPE%20html%3E%0A...%3Cstyle%3E%0Adiv%20%7B%20display%3Acontents%20%7D%0Adiv%3A%3Abefore%20%7B%20content%3A%22X%22%20%7D%0Adiv%3A%3Aafter%20%7B%20content%3A%22X%22%20%7D%0A%20%3C%2Fstyle%3E%0A%3Cdiv%3Etest%3C%2Fdiv%3E

   hayato: because shadow root is removed from the tree, slot is
   removed from the tree
   ... there’s a dilemma for that
   ... problem is we have to make the <slot> element an element
   ... can we have a new type of element for <slot>?
   ... we can style the parent elements of slots

   rniwa: i think the problem is consistency. <slot> is a weird
   element
   ... can’t get computed style, but things inside of it would be
   shown, it’s exotic

   annek: we could have a <slot> node instead of an element
   ... would it still have to be created by the HTML parser?
   ... if that’s the requirement, then it does need to be an
   element

   (someone) let’s not go there

   travis: i don’t have a problem with <slot> being an element
   ... i like having display: contents so that it’ll be there down
   the road

   annek: some engines can ship display: contents, some don’t, we
   can sort it out later

   travis: it’s like the appearance property

   domenic: (grimmace)

   elliott: if we spec it as display: contents, and then change it
   to display: block, does the slotting algorithm still place
   things underneath it?

   rniwa: it would render
   ... it’s as if you have an anonymous box around the lements

   annek: it’s not anonymous, it’s not an element

   traivs: you can give it some padding, and that would work

   annek: i think it’s okay, if mozilla and webkit ship it, and
   blink can fix it soon enough

   <annevk> [8]https://github.com/w3c/webcomponents/issues/417:
   caching vs. late binding of lifecycle callbacks

      [8] https://github.com/w3c/webcomponents/issues/417:

   annek: next: issue #417: caching vs. late binding of lifecycle
   callbacks

   domenic: if you change callback on an element, should we call
   it, instead of one on the custom element you originally
   registered
   ... i’d like to close this, it’s the only big remaining custom
   elements problem

   travis: trying to parse out the last comments on that issue

   rniwa: the main problem we had was is the inconsistency
   ... you can change other methods on an element, but not
   callbacks

   domenic: all elements go through a define step, including
   built-ins
   ... if i’m the browser, and change setAttribute before the
   built-in element is defined, that changes the behavior
   ... if i do that after it’s been registered, it doesn’t change
   the behavior
   ... same thing should apply to user code

   travis: we should impose similar restrictions on user code by
   caching (callbacks) and not allowing mutability

   annek: this sounds nice, until you consider subclasses
   ... the subclass cannot change those things
   ... mozilla has given up on finding any consistency here

   domenic: if you want to be completely consisten with regard to
   subclassing you have to protect (invariants?)

   [discussion]

   elliott: you shouldn’t do dynamic customization on a per
   element basis

   domenic: you should have to opt-in to per-element customization
   ... you can’t overwrite the click method of an <input>

   [discussion]

   rniwa: we could just freeze those attributes once define is
   called

   domenic: i don’t like modifying user classes
   ... we just got away from that

   elliott: how do you freeze these?

   rniwa: we can store the callbacks at define time
   ... there concern is that the user can modify it, all
   othermethods work, but not these (callbacks)

   travis: domenic pointed out that the user can try to modify all
   sorts of platform behavior, and that doesn’t work

   domenic: when the platform wants to create an array, it doesn’t
   call user code, it just creates an array

   [discussion of @@species as an example of user code being
   called from platform code]

   travis: the question is: is this an extension point that we
   want to create

   rniwa: if that’s the case, we should go back and make these
   symbols again
   ... then there’d be less confusion that these are special

   travis: symbols are not immutable

   elliott: symbols would have different author expectations

   <annevk> Element.attributeChanged

   <annevk> "attributeChangedCallback"

   <annevk> (latter is two characters extra, but I guess you
   typically don't need the quotes)

   annek: i think we have rough consensus, and Apple would be
   slightly sad

   domenic: these callbacks (on custom element classes) are kept
   there for subclasses

   rniwa: i’m not okay with it, but let’s just move on

   elliott: let’s move on, what’s next

   [9]https://github.com/w3c/webcomponents/issues/477:

      [9] https://github.com/w3c/webcomponents/issues/477:

   rniwa: exposing the element inside a closed shadow root doesn’t
   make sense

   annek: since open trees are exposes here and there,
   currentscript can expose them?
   ... how do we solve this, even for the closed case?
   ... it doesn’t seem ideal that you can’t get a reference to
   yourself

   rniwa: it’s hard to imagine a custom element accessing a random
   script inside it and getting a reference to itself

   elliott: script type=“module” runs in a separate scope, right?

   domenic: corret

   elliott: document.currentScript is kind of bizarre
   ... in an HTML Import, document.currentScript ends up
   referencing the script that’s being imported
   ... we should have a variable within script type=“module” for
   this instead of a currentScript global

   domenic: we can let it be null in Shadow DOM, especially
   closed, potentially open, is that right?

   elliott: there are use cases where you need to be attributes on
   a the <script> tag directly

   annek: it’s reasonable that those libraries get rewritten for
   the brave new module world
   ... maybe we should just ban this API

   rniwa: that’s a good way to go, esp. since no one’s implemented
   script type="module"

   travis: the fact that we have this global property and that’s
   sort of working already, i feel that we shouldn’t do any work
   on it to protect closed Shadow DOM
   ... closed Shadow DOM isn’t a security barrier anyway
   ... this is just another way to work around it
   ... if I really want that strong security, we have to go with
   that isolated approach
   ... not doing anything with currentScript and let it have this
   weird access seems like a bizarre case

   annek: we should resolve this as returning null
   ... this is the least objectionable path
   ... moving on

   <annevk> [10]https://github.com/w3c/webcomponents/issues/355:
   use CSS containment features by default

     [10] https://github.com/w3c/webcomponents/issues/355:

   elliott: are we okay with saying that if you put an absolute
   element inside your element, and position it outside your
   element, is it okay if it gets clipped (because of CSS
   containment)?
   ... intention of doing this is to state an opinion about the
   direction we should be moving
   ... if you encourage authors to place elements more visually,
   you get a simplified implementation and your code can be faster
   ... we could encourage authors to be fast by default

   domenic: this was just an opportunity to introduce a new
   direction

   rniwa: this would simplify delay introducing Shadow DOM in
   WebKit
   ... we don’t have this implemented

   annek: how many browsers implement `contain`?

   [discussion]

   rniwa: i think doing this for Shadow DOM is the wrong approach

   dan: we don’t about this feature being the default

   annek: sounds like we have consensus (to punt this)

   <annevk> [11]https://github.com/w3c/webcomponents/issues/186:
   integrating callback invocation with IDL and editing operations

     [11] https://github.com/w3c/webcomponents/issues/186:

   domenic: [describes a proposal related to IDL]

   rniwa: I think this is a great thing to do

   travis: i agree
   ... it would be great to have this declaratively

   domenic: okay
   ... i’ll figure it out, it’s just going to be a pain

   <annevk> [12]https://github.com/w3c/webcomponents/issues/468:
   provide a mechanism for adding default/"UA" styles to a custom
   element

     [12] https://github.com/w3c/webcomponents/issues/468:

   domenic: now that we got rid of /deep/, there’s no way to style
   an element like this

   rniwa: only question is whether we take a string, or what type?

   elliott: it can’t be inline style
   ... there’s also a proposal to have constructible stylesheets
   ... if we do this to use a string, then we can use
   constructible stylesheets when they’re finished
   ... blocking on stylesheet objects seems silly, that’s a big
   project and a ways out

   travis: this isn’t blocking v1, right?

   domenic: we could add this

   elliott: we were hoping this would be just like attaching a
   shadow root, then appendChild’ing a a style element

   travis: i was seeing this as styling the custom element itself

   domenic: the :host selector would style the element itself and
   the descendants

   elliott: it doesn’t style the descendants

   rniwa: we need to create a new context in which these (styles?)
   are evaluated
   ... we’re somewhat skeptical of this feature, it seems
   redundant
   ... we already implemented optimization that if you define the
   same style in a shadow root, and it gets reused across many
   elements, we reuse...

   domenic: this would let you do styles without having to add a
   shadow root
   ... i would like this to be at the same level of the cascade as
   UA styles
   ... this is currently impossible

   [discussion]

   elliott: providing a feature like this allows a framework to
   say, “all elements in my framework are block”, which I think is
   beneficial

   rniwa: i don’t think we object to this, but i don’t want to
   block the rest of the custom elements API on this

   annek: this shouldn’t block shipping minimum viable product

   <annevk> [13]https://github.com/w3c/webcomponents/issues/288:
   `slotchange` event

     [13] https://github.com/w3c/webcomponents/issues/288:

   domenic: this doesn’t block shipping v1

   annek: i think we all agree on using MutationObserver timing
   ... i’m assuming it wouldn’t bubble?

   elliott: are there any other microtask-timed events?

   <smaug> (does bubble or not really matter?)

   travis: promises are microtasks timed

   <smaug> (and no, this would be the first microtask timed event)

   rniwa: maybe this microtask is the timing you want to use for
   new async-type events

   annek: full-screen events don’t use task-timing

   <smaug> (and we need to remember that microtask != async from
   UA point of view. /me goes back to doing something else.)

   elliott: this seems like we’re inventing a new technology, do
   we intend to do that

   (someone) want about “blur"?

   annek: depends on the engine

   elliott: i’m not objecting to the timing here, unless we think
   this is one-off thing for slotchange

   domenic: this is mutation-to-the-DOM timing

   (someone) why isn’t this is a MO?

   travis: this generalizes it, to the point where we may not want
   it to be a MO

   annek: 1 we have multiple mutation records
   ... 2 a record is expected to carry sufficient data to reply
   what happened, which someone people don’t want here
   ... 3 if you think of Shadow DOM as a layer on top of DOM and
   should use DOM architecture
   ... the proposal is tied to how much insert/remove behave
   ... given not wanting to expose too much data, i’m okay with
   this as an event

   travis: the event and how you expect it to look after
   processing queued records, is that defined?

   annek: i’ve been waiting for this call to be over

   elliott: when do we queue the event?

   [discussion]

   elliott: let’s just do this for v1, and see what authors

   <rniwa> woot! so productive :D

   <annevk> yeah this was great

   <annevk> thanks everyone

   <dglazkov> \o/

   <rniwa> jan: thanks for scribing!

   [End of minutes]
     __________________________________________________________



--
Charles McCathie Nevile - web standards - CTO Office, Yandex
 cha...@yandex-team.ru - - - Find more at http://yandex.com

Reply via email to