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perf: reduce some repeated logic (#4814) #4821

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Merged
JoviDeCroock merged 1 commit into from
Jun 28, 2025
Merged

perf: reduce some repeated logic (#4814) #4821

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42 changes: 12 additions & 30 deletions src/diff/children.js
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Original file line number Diff line number Diff line change
Expand Up @@ -407,6 +407,7 @@ function findMatchingIndex(
const key = childVNode.key;
const type = childVNode.type;
let oldVNode = oldChildren[skewedIndex];
const matched = oldVNode != NULL && (oldVNode._flags & MATCHED) == 0;

// We only need to perform a search if there are more children
// (remainingOldChildren) to search. However, if the oldVNode we just looked
Expand All @@ -421,45 +422,26 @@ function findMatchingIndex(
// we should not search as we risk re-using state of an unrelated VNode. (reverted for now)
let shouldSearch =
// (typeof type != 'function' || type === Fragment || key) &&
remainingOldChildren >
(oldVNode != NULL && (oldVNode._flags & MATCHED) == 0 ? 1 : 0);
remainingOldChildren > (matched ? 1 : 0);

if (
(oldVNode === NULL && childVNode.key == null) ||
(oldVNode &&
key == oldVNode.key &&
type == oldVNode.type &&
(oldVNode._flags & MATCHED) == 0)
(matched && key == oldVNode.key && type == oldVNode.type)
) {
return skewedIndex;
} else if (shouldSearch) {
let x = skewedIndex - 1;
let y = skewedIndex + 1;
while (x >= 0 || y < oldChildren.length) {
if (x >= 0) {
oldVNode = oldChildren[x];
if (
oldVNode &&
(oldVNode._flags & MATCHED) == 0 &&
key == oldVNode.key &&
type == oldVNode.type
) {
return x;
}
x--;
}

if (y < oldChildren.length) {
oldVNode = oldChildren[y];
if (
oldVNode &&
(oldVNode._flags & MATCHED) == 0 &&
key == oldVNode.key &&
type == oldVNode.type
) {
return y;
}
y++;
const childIndex = x >= 0 ? x-- : y++;
oldVNode = oldChildren[childIndex];
if (
oldVNode != NULL &&
(oldVNode._flags & MATCHED) == 0 &&
key == oldVNode.key &&
type == oldVNode.type
) {
return childIndex;
}
}
}
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