js-set-map-lookups

Replace array.includes() with Set.has() for O(1) constant-time lookups instead of O(n) scans. Set membership checks are dramatically faster on large collections because they use hash-based lookup rather than linear iteration.

Use Set when you perform frequent membership tests on collections with many items. Set.has() stays fast regardless of size, while array.includes() slows down proportionally. For small arrays checked once, the difference is negligible.

Yes. Initialize a Set from your array with new Set(array), then replace item.includes(value) with set.has(value). Both use native JavaScript with no dependencies, making the conversion straightforward in any JavaScript or TypeScript project.

Create a Set from allowed IDs, then filter the collection using set.has() to check each item. This pattern executes in linear time with constant-time lookups, replacing slower array.includes() filtering that performs quadratic operations.

Set stores unique values and checks membership with has(). Map stores key-value pairs and checks keys with has(). Both offer O(1) lookup; use Set for membership tests and Map when you need to associate data with each item.

Yes. Set and Map are native JavaScript structures with full TypeScript support. You can use generic types like Set<string> or Map<string, number> to ensure type safety while maintaining O(1) performance.