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ladybird/Tests/LibWeb/Text/input/css-has-invalidation/has-child-combinator.html
Andreas Kling 85ff13870f LibWeb: Stop :has() invalidation walk when out of :has() scope
A DOM mutation under a document that uses any :has() rule currently
walks every ancestor up to the root, invoking invalidate_style_if_
affected_by_has() on each. Most of those ancestors have nothing to
do with :has(), so the work scales linearly with DOM depth.

Introduce an in_has_scope flag on Element, set while evaluating :has()
arguments for invalidation metadata. StyleScope's upward invalidation
walk now terminates at the first element that is neither in :has()
scope nor a :has() anchor, so it only traverses the region where some
:has() rule might actually care about the change.

Keep the existing fast :has() matching paths for normal selector
matching, but bypass them while collecting per-element metadata so the
scope markers still get populated. Node insertion also schedules the
parent for the :has() walk so newly inserted nodes still reach the real
anchor.

The css-has-invalidation suite adds focused coverage for these shapes
and updates the expected counters to reflect the shorter walks.
2026-04-20 13:20:41 +02:00

31 lines
1.1 KiB
HTML

<!DOCTYPE html>
<script src="../include.js"></script>
<script src="_helpers.js"></script>
<style>
.anchor:has(> .match) { color: red; }
</style>
<div class="anchor" id="anchor">
<div id="child">
<span id="grandchild">grandchild</span>
</div>
</div>
<script>
test(() => {
settleAndReset();
// Adding .match to a direct child should invalidate.
document.getElementById("child").classList.add("match");
getComputedStyle(document.getElementById("anchor")).color;
printCounters("add .match to direct child");
internals.resetStyleInvalidationCounters();
// Adding .match to a grandchild is NOT enough for :has(> .match);
// the anchor should stay unstyled. The walker may still run if the
// grandchild is in_has_scope (walked during initial match attempt).
document.getElementById("grandchild").classList.add("match");
getComputedStyle(document.getElementById("anchor")).color;
printCounters("add .match to grandchild (should not style anchor)");
});
</script>