Tiled UTFGrid

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var key = 'Your Mapbox access token from http://mapbox.com/ here';

var mapLayer = new ol.layer.Tile({
  source: new ol.source.TileJSON({
    url: 'https://api.tiles.mapbox.com/v4/mapbox.geography-class.json?secure&access_token=' + key
  })
});

var gridSource = new ol.source.TileUTFGrid({
  url: 'https://api.tiles.mapbox.com/v4/mapbox.geography-class.json?secure&access_token=' + key
});

var gridLayer = new ol.layer.Tile({source: gridSource});

var view = new ol.View({
  center: [0, 0],
  zoom: 1
});

var mapElement = document.getElementById('map');
var map = new ol.Map({
  layers: [mapLayer, gridLayer],
  target: mapElement,
  view: view
});

var infoElement = document.getElementById('country-info');
var flagElement = document.getElementById('country-flag');
var nameElement = document.getElementById('country-name');

var infoOverlay = new ol.Overlay({
  element: infoElement,
  offset: [15, 15],
  stopEvent: false
});
map.addOverlay(infoOverlay);

map.on('pointermove', function(evt) {
  if (evt.dragging) {
    return;
  }
  var coordinate = map.getEventCoordinate(evt.originalEvent);
  displayCountryInfo(coordinate);
});

map.on('click', function(evt) {
  displayCountryInfo(evt.coordinate);
});

<!DOCTYPE html>
<html>
  <head>
    <title>Tiled UTFGrid</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v4.6.4/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/v4.6.4/build/ol.js"></script>
    <style>
      #country-name {
        color: black;
        font-size: 12pt;
        font-weight: bold;
        text-shadow: white 0.1em 0.1em 0.2em;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <div style="display: none;">
      <!-- Overlay with the country info -->
      <div id="country-info">
        <div id="country-name">&nbsp;</div>
        <img id="country-flag" src="" />
      </div>
    </div>
    <script>
      var key = 'Your Mapbox access token from http://mapbox.com/ here';

      var mapLayer = new ol.layer.Tile({
        source: new ol.source.TileJSON({
          url: 'https://api.tiles.mapbox.com/v4/mapbox.geography-class.json?secure&access_token=' + key
        })
      });


      var gridSource = new ol.source.TileUTFGrid({
        url: 'https://api.tiles.mapbox.com/v4/mapbox.geography-class.json?secure&access_token=' + key
      });

      var gridLayer = new ol.layer.Tile({source: gridSource});

      var view = new ol.View({
        center: [0, 0],
        zoom: 1
      });

      var mapElement = document.getElementById('map');
      var map = new ol.Map({
        layers: [mapLayer, gridLayer],
        target: mapElement,
        view: view
      });

      var infoElement = document.getElementById('country-info');
      var flagElement = document.getElementById('country-flag');
      var nameElement = document.getElementById('country-name');

      var infoOverlay = new ol.Overlay({
        element: infoElement,
        offset: [15, 15],
        stopEvent: false
      });
      map.addOverlay(infoOverlay);

      var displayCountryInfo = function(coordinate) {
        var viewResolution = /** @type {number} */ (view.getResolution());
        gridSource.forDataAtCoordinateAndResolution(coordinate, viewResolution,
            function(data) {
              // If you want to use the template from the TileJSON,
              //  load the mustache.js library separately and call
              //  info.innerHTML = Mustache.render(gridSource.getTemplate(), data);
              mapElement.style.cursor = data ? 'pointer' : '';
              if (data) {
                flagElement.src = 'data:image/png;base64,' + data['flag_png'];
                nameElement.innerHTML = data['admin'];
              }
              infoOverlay.setPosition(data ? coordinate : undefined);
            });
      };

      map.on('pointermove', function(evt) {
        if (evt.dragging) {
          return;
        }
        var coordinate = map.getEventCoordinate(evt.originalEvent);
        displayCountryInfo(coordinate);
      });

      map.on('click', function(evt) {
        displayCountryInfo(evt.coordinate);
      });
    </script>
  </body>
</html>