perf: fix O(n*m) dedup in querySelectorAll#12
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borgar merged 1 commit intoborgar:masterfrom Feb 16, 2026
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The deduplication step after selector matching did this:
```ts
contextNode.getElementsByTagName('*')
.filter(elm => elements.includes(elm))
```
This traverses the entire tree and does a linear .includes() scan per element.
That makes it O(n*m) where n is the tree size and m is the number of matched
elements. For large documents with many matches (e.g. querySelectorAll on a
sheet with thousands of cells), this can get quite bad.
For single-group selectors (no commas), the filter chain already produces
results in document order, so skip the tree walk entirely and just deduplicate
seen elements in-place with a Set.
For multi-group (comma) selectors, keep the tree walk for document order but
collect matched elements into a `Set` up front and use `Set.has()` for O(1)
lookups.
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Awesome! |
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What
Fix O(n*m) performance in
domQueryHow
The deduplication step after selector matching did this:
This traverses the entire tree and does a linear
.includes()scan per element. That makes it O(n*m) where n is the tree size and m is the number of matched elements. For large documents with many matches (e.g.querySelectorAllon a sheet with thousands of cells), this can get quite bad.For single-group selectors (no commas), the filter chain already produces results in document order, so skip the tree walk entirely and just deduplicate seen elements in-place with a Set.
For multi-group selectors (i.e. with commas), keep the tree walk for document order but collect matched elements into a
Setup front and useSet.has()for O(1) lookups.