Filter by marker type

Using setFilter, lookup the type of marker to be displayed on a map.

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Filter by marker type</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src='https://api.mapbox.com/mapbox.js/v3.0.1/mapbox.js'></script>
<link href='https://api.mapbox.com/mapbox.js/v3.0.1/mapbox.css' rel='stylesheet' />
<style>
  body { margin:0; padding:0; }
  #map { position:absolute; top:0; bottom:0; width:100%; }
</style>
</head>
<body>
<style>
.filter-ui {
  background:#fff;
  position:absolute;
  top:10px;
  right:10px;
  z-index:100;
  padding:10px;
  border-radius:3px;
  }
</style>

<nav id='filters' class='filter-ui'></nav>
<div id='map'></div>
<script>
L.mapbox.accessToken = '<your access token here>';
var map = L.mapbox.map('map', 'mapbox.dc-markers');

// Find and store a variable reference to the list of filters.
var filters = document.getElementById('filters');

// Wait until the marker layer is loaded in order to build a list of possible
// types. If you are doing this with another featureLayer, you should change
// map.featureLayer to the variable you have assigned to your featureLayer.
map.featureLayer.on('ready', function() {
  // Collect the types of symbols in this layer. you can also just
  // hardcode an array of types if you know what you want to filter on,
  // like var types = ['foo', 'bar'];
  var typesObj = {}, types = [];
  var features = map.featureLayer.getGeoJSON().features;
  for (var i = 0; i < features.length; i++) {
    typesObj[features[i].properties['marker-symbol']] = true;
  }
  for (var k in typesObj) types.push(k);

  var checkboxes = [];
  // Create a filter interface.
  for (var i = 0; i < types.length; i++) {
    // Create an an input checkbox and label inside.
    var item = filters.appendChild(document.createElement('div'));
    var checkbox = item.appendChild(document.createElement('input'));
    var label = item.appendChild(document.createElement('label'));
    checkbox.type = 'checkbox';
    checkbox.id = types[i];
    checkbox.checked = true;
    // create a label to the right of the checkbox with explanatory text
    label.innerHTML = types[i];
    label.setAttribute('for', types[i]);
    // Whenever a person clicks on this checkbox, call the update().
    checkbox.addEventListener('change', update);
    checkboxes.push(checkbox);
  }

  // This function is called whenever someone clicks on a checkbox and changes
  // the selection of markers to be displayed.
  function update() {
    var enabled = {};
    // Run through each checkbox and record whether it is checked. If it is,
    // add it to the object of types to display, otherwise do not.
    for (var i = 0; i < checkboxes.length; i++) {
      if (checkboxes[i].checked) enabled[checkboxes[i].id] = true;
    }
    map.featureLayer.setFilter(function(feature) {
      // If this symbol is in the list, return true. if not, return false.
      // The 'in' operator in javascript does exactly that: given a string
      // or number, it says if that is in a object.
      // 2 in { 2: true } // true
      // 2 in { } // false
      return (feature.properties['marker-symbol'] in enabled);
    });
  }
});
</script>
to create your own custom map and use it in this example.
Use this example by copying its source into your own HTML page and replacing the Map ID with one of your own from your projects. Having trouble with JavaScript? Try out Codecademy or contact our support team.
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