TopoJSON

Demonstrates rendering of features from a TopoJSON topology.

This example uses a vector layer with ol.format.TopoJSON for rendering features from TopoJSON.

<!DOCTYPE html>
<html>
  <head>
    <title>TopoJSON</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v3.20.0/css/ol.css" type="text/css">
    <!-- The line below is only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v2/polyfill.min.js?features=requestAnimationFrame,Element.prototype.classList,URL"></script>
    <script src="https://openlayers.org/en/v3.20.0/build/ol.js"></script>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script>
      var raster = new ol.layer.Tile({
        source: new ol.source.TileJSON({
          url: 'https://api.tiles.mapbox.com/v3/mapbox.world-dark.json?secure'
        })
      });

      var style = new ol.style.Style({
        fill: new ol.style.Fill({
          color: 'rgba(255, 255, 255, 0.6)'
        }),
        stroke: new ol.style.Stroke({
          color: '#319FD3',
          width: 1
        })
      });

      var vector = new ol.layer.Vector({
        source: new ol.source.Vector({
          url: 'https://openlayers.org/en/v3.20.0/examples/data/topojson/world-110m.json',
          format: new ol.format.TopoJSON(),
          overlaps: false
        }),
        style: function(feature) {
          // don't want to render the full world polygon, which repeats all countries
          return feature.getId() !== undefined ? style : null;
        }
      });

      var map = new ol.Map({
        layers: [raster, vector],
        target: 'map',
        view: new ol.View({
          center: [0, 0],
          zoom: 1
        })
      });
    </script>
  </body>
</html>