In the next example, called
ch09_turf, we will extend our application's topological capabilities with Turf. Turf is a well-documented, simple, but capable, library for geospatial analysis. All the basic topological functions are in the library along with some more advanced and scarce functions. Turf uses GeoJSON not only as its exchange format but also as its internal format. This enables it to skip the overhead caused by data conversion.
You can grab the most recent version of Turf from the GitHub repository at https://github.com/Turfjs/turf/releases.