turf.booleanWithin
What is turf.booleanWithin?
turf.booleanWithin tests whether geometry a is completely inside geometry b. It is the inverse of turf.booleanContains — booleanWithin(a, b) equals booleanContains(b, a).
turf.booleanWithin(feature1, feature2) → booleanWhen would you use turf.booleanWithin?
Use turf.booleanWithin when filtering from the contained side — "is my point, line, or polygon entirely within this region?". In code that thinks from the inner feature's perspective (e.g. each order being tested against its zone) it reads more naturally than booleanContains.
const inBounds = customers.features.filter(c => turf.booleanWithin(c, cityPolygon));FAQs
How do I install Turf.js to use this function?
Install npm install @turf/boolean-within and import import { booleanWithin } from '@turf/boolean-within', or use turf.booleanWithin from @turf/turf.
Does a point on the boundary count as within?
The OGC predicate requires the inner geometry's interior to be strictly inside the outer geometry's interior. Boundary-only contact is not enough. Use turf.booleanIntersects if touching counts.
Does it support MultiPolygon outer geometries?
Yes. A point or polygon inside any of a MultiPolygon's parts is within the whole.
When should I use booleanWithin vs booleanPointInPolygon?
For single-point checks, booleanPointInPolygon is faster and offers ignoreBoundary. Use booleanWithin for line-in-polygon or polygon-in-polygon checks.
