CartoDB Layer selector by wboykinm

index.html

<!DOCTYPE html>
<html>
  <head>
    <style>
      html, body, #map {
        height: 100%;
        padding: 0;
        margin: 0;
      }

      #layer_selector {
        position: absolute;
        top: 20px;
        right: 20px;
        padding: 0;
      }
      #layer_selector ul {
        padding: 0; margin: 0;
        list-style-type: none;
      }
      #layer_selector li {
        border-bottom: 1px solid #999999;
        padding: 15px 30px;
        font-family: "Helvetica",Arial;
        font-size: 13px;
        color: #444;
        cursor: auto;
      }
      #layer_selector li:hover {
        background-color: #F0F0F0;
        cursor: pointer;
      }
      #layer_selector li.selected {
        background-color: #EEE;
      }
    </style>

    <link rel="stylesheet" href="//libs.cartocdn.com/cartodb.js/v2/themes/css/cartodb.css" />
    <!--[if lte IE 8]>
        <link rel="stylesheet" href="//libs.cartocdn.com/cartodb.js/v2/themes/css/cartodb.ie.css" />
    <![endif]-->

  </head>
    
  <body>
    <div id="map"></div>
    <div id="layer_selector" class="cartodb_infobox">
      <ul>
        <li data="all" class="selected">All countries</li>
        <li data="1000">area >1000 km<sup>2</sup></li>
        <li data="6000">area >6000 km<sup>2</sup></li>
        <li data="10000">area >10000 km<sup>2</sup></li>
        <li data="50000">area >50000 km<sup>2</sup></li>
      </ul>
    </div>
  </body>

  <!-- include cartodb.js library -->
  <script src="//libs.cartocdn.com/cartodb.js/v2/cartodb.js"></script>

  <script>

    // create layer selector
    function createSelector(layer) {
      var sql = new cartodb.SQL({ user: 'examples' });

      var $options = $('#layer_selector li');
      $options.click(function(e) {

        // get the area of the selected layer
        var $li = $(e.target);
        var area = $li.attr('data');

        // deselect all and select the clicked one
        $options.removeClass('selected');
        $li.addClass('selected');

        // create query based on data from the layer
        var query = "select * from european_countries_e";
        if(area !== 'all') {
          query = "select * from european_countries_e where area > " + area;
        }

        // change the query in the layer to update the map
        layer.setQuery(query);
      });
    }

    function main() {
      cartodb.createVis('map', '//examples.cartodb.com/api/v1/viz/european_countries_e/viz.json', {
          tiles_loader: true,
          center_lat: 50,
          center_lon: 20,
          zoom: 3
      })
      .done(function(vis, layers) {
        // layer 0 is the base layer, layer 1 is cartodb layer
        createSelector(layers[1])
      })
      .error(function(err) {
        console.log(err);
      });


    }

    window.onload = main;

  </script>


</html>