turf.lineSliceAlong

What is turf.lineSliceAlong?

turf.lineSliceAlong returns the portion of a LineString between a starting distance and a stopping distance measured along the line from its first vertex.

turf.lineSliceAlong(line, startDist, stopDist, options?) → Feature<LineString>

Options include:

• units — 'kilometers' (default), 'meters', 'miles', 'nauticalmiles', 'radians', 'degrees'

When would you use turf.lineSliceAlong?

Use turf.lineSliceAlong when you reference positions by distance — animating progress along a route by slicing from 0 to the current distance each frame, extracting milepost-based stretches of a highway, or slicing a track based on elapsed time converted to distance.

In Node.js, it is a direct tool for linear referencing workflows where events are stored as "start at X km, end at Y km" and you want to materialise the geometry corresponding to that range.

import lineSliceAlong from '@turf/line-slice-along';

FAQs

What if stopDist exceeds the line length?

The slice is clamped at the end of the line — you get the portion from startDist to the endpoint.

How do I install just lineSliceAlong?

npm install @turf/line-slice-along. It depends on @turf/helpers, @turf/invariant, and @turf/bearing.

Does the slice start and end snap to existing vertices?

No — new vertices are inserted at the exact slice positions, which may land between existing vertices. The result is a new LineString with clean endpoints.

How does this differ from turf.along?

turf.along returns a single point at a given distance. turf.lineSliceAlong returns the sub-line between two distances. Use along for markers; use lineSliceAlong for highlighted sections.