K-d tree (demo)

!demo

``js
var KDTree = require('k-d-tree');
var geoJSON = {
"type": "FeatureCollection",
"features": [{
"geometry": {
"type": "Point",
"coordinates": [-176.633, 51.883]
},
"type": "Feature",
"properties": {
"wikipedia": "Adak,_Alaska",
"city": "Adak"
},
"id": "Adak"
}, {
"geometry": {
"type": "Point",
"coordinates": [-175.2, -21.133]
},
"type": "Feature",
"properties": {
"wikipedia": "Nuku%CA%BBalofa",
"city": "Nuku%CA%BBalofa"
},
"id": "Nuku%CA%BBalofa"
},
...
{
"geometry": {
"type": "Point",
"coordinates": [-171.833, -13.833]
},
"type": "Feature",
"properties": {
"wikipedia": "Apia",
"city": "Apia"
},
"id": "Apia"
}]
}

function distance(a, b){
return map.options.crs.distance(L.latLng(a), L.latLng(b));
}

var tree = new KDTree(geoJSON.features.map(function(f) {
var ref = f.geometry.coordinates.slice().reverse();
f.feature = f;
return f;
}), distance, [0, 1]);
``

based on kd-tree-javascript by @aemkei

2015