dochuts.js

var huts = new L.MarkerClusterGroup({
  showCoverageOnHover: false,
  maxClusterRadius: 50
});

var hutTypes = ['Basic Hut/Bivvy', 'Standard Hut', 'Serviced Hut', 'Serviced-Alpine Hut', 'Great Walk Hut'];

huts.addLayers(data.map(function(hut) {
  return new L.Marker(new L.LatLng(hut[0], hut[1]), {
    title: hut[2],
    icon: L.icon({
      iconSize: [32, 37],
      iconAnchor: [16, 37],
      popupAnchor:  [0, -30],
      iconUrl: 'icons/hut' + hut[3] + '.png'
    })
  }).bindPopup('<strong>' + hut[2] + '</strong><br>' + hutTypes[hut[3]]);
}));