How do I toggle a legend of a cartodb layer in a leaflet map?

Question

Per my previous question - here - how do I get the legend to toggle (I have it turned off now) in conjunction with toggling the cartodb layer via the leaflet layer control? Maybe adding it as a variable some way?

  var cdb_url = 'http://ovrdc.cartodb.com/api/v2/viz/52a89830-a8c1-11e4-b072-0e0c41326911/viz.json';
  cartodb.createLayer(map, cdb_url, {legends:false})
    .addTo(map)
    .on('done', function(crashes) {
      crashes.setZIndex(2);
      var overlayMaps = {
        "Vehicle Crashes": crashes
      };
      L.control.layers(baseMaps, overlayMaps, {collapsed: false}).addTo(map);
    })
    .on('error', function(err) {
      alert("some error occurred: " + err);
    });

Answer 1

I suggest setting up an empty object to hold the cartodb layers

var cdb_layers = {}

Then, each time you add a cartodb layer, on done(), update the object with a reference to the layer:

cdb_layers['crashes'] = layer;

This gives you the overlays structure you need to create the L.control.layers. Only construct the L.control.layers after all of your cartodb layers are loaded.

updated fiddle