Awesome
geoflatbush
A geographic extension for flatbush, a very fast static 2D spatial index. Performs nearest neighbors queries for geographic bounding boxes, taking Earth curvature and date line wrapping into account. Similar to geokdbush, but for boxes instead of points.
import {around} from 'geoflatbush';
around(index, 30.5, 50.5, 10); // return 10 nearest boxes to Kyiv