⚡ Bolt: Optimize CSV string generation - #4470
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Replaced chained `.map().join()` with a single-pass `for` loop and string concatenation in `downloadCsv`. This eliminates intermediate array allocations per row, significantly reducing garbage collection overhead and memory usage during large CSV exports. Co-authored-by: dieterolson <198168927+dieterolson@users.noreply.github.com>
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| // to avoid allocating intermediate arrays on every row with .map().join(). | ||
| let csvString = ""; | ||
| for (let i = 0; i < headers.length; i++) { | ||
| csvString += escapeCsvValue(headers[i]); |
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When callers create typed arrays by setting .length or assigning only selected indices, the existing .some guards accept those sparse arrays, but this direct indexed access passes each hole through String(undefined) and exports the literal text undefined. The previous .map().join() implementation serialized holes as empty CSV fields, so preserve that behavior or reject sparse arrays during boundary validation.
AGENTS.md reference: AGENTS.md:L129-L133
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💡 What: Replaced chained array methods (
.map().join()) with a single-passforloop and string concatenation indownloadCsv.🎯 Why: To eliminate intermediate array allocations for every row during CSV generation, reducing garbage collection pressure and memory usage, especially for large datasets.
📊 Impact: Reduces memory allocation overhead during CSV export.
🔬 Measurement: Verify CSV export functionality still produces the correct output format without generating intermediate arrays.
PR created automatically by Jules for task 16696205610984217258 started by @dieterolson