Add IntersectionObserver target requirement to Event Loops Processing Model #8016
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…as no pending initial IntersectionObserver targets before skipping rendering.
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PTAL @domenic -- thanks in advance! |
| <li>The user agent believes that updating the rendering of the <code>Document</code>'s <span | ||
| data-x="concept-document-bc">browsing context</span> would have no visible effect, and</li> | ||
| <li>The <code>Document</code>'s <span>map of animation frame callbacks</span> is empty.</li> | ||
| <li> | ||
| <p>The <code>Document</code> does not have <span>pending initial IntersectionObserver |
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| <p>The <code>Document</code> does not have <span>pending initial IntersectionObserver | |
| <p>The <code>Document</code> does not have <span>pending initial <code>IntersectionObserver</code> |
| <p>The <code>Document</code> does not have <span>pending initial IntersectionObserver | ||
| targets</span>.</p> | ||
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| <p>A <code>Document</code> is said to have <dfn>pending initial IntersectionObserver |
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| <p>A <code>Document</code> is said to have <dfn>pending initial IntersectionObserver | |
| <p>A <code>Document</code> <var>document</var> is said to have <dfn>pending initial <code>IntersectionObserver</code> |
| targets</span>.</p> | ||
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| <p>A <code>Document</code> is said to have <dfn>pending initial IntersectionObserver | ||
| targets</dfn> if there is at least one <span>IntersectionObserver</span> meeting these |
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| targets</dfn> if there is at least one <span>IntersectionObserver</span> meeting these | |
| targets</dfn> if there is at least one <code>IntersectionObserver</code> <var>observer</var> meeting these |
| targets</dfn> if there is at least one <span>IntersectionObserver</span> meeting these | ||
| criteria:</p> | ||
| <ol class="brief"> | ||
| <li>The <span data-x="IntersectionObserver">observer</span>'s <span |
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| <li>The <span data-x="IntersectionObserver">observer</span>'s <span | |
| <li><var>observer</var>'s <span |
| criteria:</p> | ||
| <ol class="brief"> | ||
| <li>The <span data-x="IntersectionObserver">observer</span>'s <span | ||
| data-x="dom-IntersectionObserver-root">root</span> is in the <code>Document</code> (for |
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"is in the Document" is not precise enough. For example, how does this interact with shadow DOM?
I suspect you want to check if its [shadow-including root] is document.
| <p>A <code>Document</code> is said to have <dfn>pending initial IntersectionObserver | ||
| targets</dfn> if there is at least one <span>IntersectionObserver</span> meeting these | ||
| criteria:</p> | ||
| <ol class="brief"> |
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| <ol class="brief"> | |
| <ul class="brief"> |
| <li>The <span data-x="IntersectionObserver">observer</span>'s <span | ||
| data-x="dom-IntersectionObserver-root">root</span> is in the <code>Document</code> (for | ||
| the <span>top-level browsing context</span>, this includes any <span | ||
| data-x="implicit root observer">implicit root observers</span>).</li> |
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I don't understand this parenthetical at all. Parentheticals usually restate what's previous to them, but from what I can tell this is just a totally different criterion. It's saying something like "in addition to the two bullet points here, a Document also has pending initial IntersectionObserver targets if its browsing context is a top-level browsing context and there exists any IntersectionObserver whose root is null."
But even that doesn't make sense... What if there's an IntersectionObserver with null root in tab A, and tab B is a top-level browsing context whose Document we're considering? You need to scope this to the Document under consideration somehow. And I don't see how to do that, if the IntersectionObserver's root is null... then it has no connection to a Document, and it's just floating freely, disconnected from any document or browsing context.
This might just be something very broken about the IntersectionObserver spec?
| <li> The <span data-x="IntersectionObserver">observer</span> has at least one | ||
| <em>target</em> in its <span data-x="dom-IntersectionObserver-observedtargets-slot"> | ||
| ObservationTargets slot</span> for which no <span>IntersectionObserverEntry</span> has | ||
| yet been queued.</li> |
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I don't understand what the latter part of this sentence means. So I have an observer, and I look at observer.[[ObservationTargets]]. That's a list... of what, the IntersectionObserver spec doesn't say. But how do I go from a target object target, to a boolean saying whether or not an IntersectionObserverEntry has been queued for that target? Do I need to loop over some global list of queued IntersectionObserverEntrys? Where is that list?
| <em>target</em> in its <span data-x="dom-IntersectionObserver-observedtargets-slot"> | ||
| ObservationTargets slot</span> for which no <span>IntersectionObserverEntry</span> has | ||
| yet been queued.</li> | ||
| </ol> |
https://w3c.github.io/IntersectionObserver/#pending-initial-observation describes an additional requirement for skipping document rendering in the HTML Event Loops Processing Model, one which is not documented in the Unnecessary rendering portion of the Update the rendering step. This change adds this requirement directly to the processing model spec.
I'll follow up with a corresponding change to w3c/IntersectionObserver to close corresponding issue w3c/IntersectionObserver#498.
Fixes #8015
/infrastructure.html ( diff )
/webappapis.html ( diff )