Two-dimensional recursive spatial subdivision

 A quadtree recursively partitions two-dimensional space into squares, dividing
 each square into four equally-sized squares. Each distinct point exists in a
 unique leaf node; coincident points are represented by a linked list.
 .
 Quadtrees can accelerate various spatial operations, such as the Barnes–Hut
 approximation for computing many-body forces, collision detection, and
 searching for nearby points.
 .
 Node.js is an event-based server-side JavaScript engine.