TurfJS

Turf.js is an advanced geospatial analysis library for JavaScript that performs GIS operations entirely in the browser or Node.js environment. The modular library provides functions for spatial analysis including measurements, transformations, joins, and classifications of geographic data. Turf.js works with GeoJSON data structures and can perform operations like calculating distances, creating buffers, finding points within polygons, and generating voronoi diagrams. It's commonly used in mapping applications built with Leaflet, Mapbox GL JS, and OpenLayers to add analytical capabilities. The library is particularly valuable for applications requiring client-side spatial analysis without server dependencies. Turf.js is open source and maintained by an active community of geospatial developers. Use cases range from location-based services to environmental analysis and urban planning tools.