perf(render): clear the render area with replaceChildren() - #4936
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lukecotter wants to merge 1 commit into
Draft
perf(render): clear the render area with replaceChildren()#4936lukecotter wants to merge 1 commit into
lukecotter wants to merge 1 commit into
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Replace the `while(element.firstChild) removeChild(...)` loops in VirtualDomVertical.clearRows / _virtualRenderFill and BasicVertical.clearRows with a single native element.replaceChildren() call, avoiding N individual DOM mutations per clear.
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Change
Replace the three
while(element.firstChild) element.removeChild(element.firstChild)loops — in
VirtualDomVertical.clearRows,VirtualDomVertical._virtualRenderFillandBasicVertical.clearRows— with a single nativeelement.replaceChildren().Honest reporting of the measurement
The benchmark tier cannot see this change. Measured on its own build at 500k rows,
K=5, medians:
rerenderInPlacemetricThe granular-scroll and tree-rerender scenarios are identical to master on every
counter (s1Churn 240, s1Nodes 48, s1Batches 24; nodesCollapse/nodesExpand 120/120).
The reason is that the
nodescounter measures rows moved, andreplaceChildren()moves the same rows. The saving is in the number of native DOM calls, which no
counter in the harness reports, and
msClearat 11.0 → 11.4 with 15.7% relativestandard deviation is noise in both directions.
So the claim rests on
test/unit/core/VirtualDomVertical.clearRows.spec.jsand on thisbeing strictly fewer native calls for the same result. It is a call-count and clarity
change, not a measurable speed-up. Draft because it is part of a larger renderer
series; happy for it to be judged on that basis alone.
Note
The companion virtual-renderer rewrite PR in this series also uses
replaceChildren()in
VirtualDomVertical, so expect a conflict there. Only theBasicVertical.jschangeis unique to this PR.