turf.intersect

What is turf.intersect?

turf.intersect returns the shared area of two polygons as a Polygon or MultiPolygon — or null if they do not overlap. It is the spatial-operations equivalent of ST_Intersection in PostGIS and is built on the robust polygon-clipping library.

turf.intersect(featureCollection) → Feature<Polygon | MultiPolygon> | null

Recent versions accept a FeatureCollection<Polygon> with two features; older versions took two arguments. Check the package version in your project.

When would you use turf.intersect?

Use turf.intersect for any "region A that is also inside region B" query — for example, clipping a dataset to a selection polygon, computing the overlap between a hazard zone and a land parcel, or intersecting a user-drawn region with administrative boundaries to drive a filter UI.

In Node.js ETL, it is the primitive for land-cover classification, overlap analysis, and spatial joins where you need the geometry of the overlap (not just whether they intersect — for that use turf.booleanIntersects).

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FAQs

What is returned when polygons do not overlap?

null. Always guard against null before passing the result to a map source or downstream operation.

How do I install just intersect?

npm install @turf/intersect. It depends on @turf/helpers and polygon-clipping.

Does it handle holes and MultiPolygon?

Yes. The underlying algorithm handles polygons with holes and MultiPolygon inputs, producing topologically valid results with correct winding.

Do I want intersect or booleanIntersects?

Use turf.intersect when you need the overlap geometry. Use turf.booleanIntersects when you only need a yes/no — it is significantly faster because it bails out on the first shared point.