map.js

// Create map layers
var layers = {
  'Seafloor': L.tileLayer('tiles/nz-seafloor/{z}/{x}/{y}.png', {
    maxZoom: 9, 
    attribution: '<a href="http://www.niwa.co.nz/our-science/oceans/bathymetry">NIWA</a>'
  }),

  'Topographic': L.tileLayer('tiles/nz-topo/{z}/{x}/{y}.png', {
    attribution: '<a href="http://data.linz.govt.nz/">LINZ</a>, <a href="http://lris.scinfo.org.nz/">LRIS</a>'
  }),

  'Tour': L.cartoDB('http://thematicmapping.cartodb.com/api/v2/sql?q=SELECT * FROM new_zealand_tour', {
    pointToLayer: function(feature, latlng) {
      return L.marker(latlng, {
        icon: L.icon({
          iconSize: [27, 27],
          iconAnchor: [13, 27],
          popupAnchor:  [1, -24], 
          iconUrl: 'icons/' + feature.properties.icon + '.png'
        })
      })
    },
    onEachFeature: function(feature, layer) {
      layer.bindPopup('<strong>' + feature.properties.name + '</strong><br>' + (feature.properties.description ? feature.properties.description : ''));
    }
  })
};

// Get url parameters
var params = {};
window.location.href.replace(/[?&]+([^=&]+)=([^&]*)/gi, function(m, key, value) {
  params[key] = value;
});

if (params.layers) {
  var activeLayers = params.layers.split(',').map(function(item) { // map function not supported in IE < 9
    return layers[item];
  });
}

// Create map
var map = new L.Map('map', {
  center: [params.lat || -41.2728, params.lng || 173.2996], 
  minZoom: 4,
  maxZoom: 12,	
  zoom: params.zoom || 6,
  layers: activeLayers || [layers.Seafloor, layers.Topographic]
});

map.attributionControl.setPrefix('<a href="http://blog.thematicmapping.org/">thematic mapping blog</a>');

// Add controls
L.control.scale().addTo(map);
L.control.layers({}, layers).addTo(map);