Select Features

Example of using the Select interaction.

Choose between Single-click, Click, Hover and Alt+Click as the event type for selection in the combobox below. When using Single-click or Click you can hold do Shift key to toggle the feature in the selection.

Note: when Single-click is used double-clicks won't select features. This in contrast to Click, where a double-click will both select the feature and zoom the map (because of the DoubleClickZoom interaction). Note that Single-click is less responsive than Click because of the delay it uses to detect double-clicks.

In this example, a listener is registered for the Select interaction's select event in order to update the selection status above.

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import Map from 'ol/Map.js';
import View from 'ol/View.js';
import {click, pointerMove, altKeyOnly} from 'ol/events/condition.js';
import GeoJSON from 'ol/format/GeoJSON.js';
import Select from 'ol/interaction/Select.js';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer.js';
import OSM from 'ol/source/OSM.js';
import VectorSource from 'ol/source/Vector.js';

var raster = new TileLayer({
  source: new OSM()
});

var vector = new VectorLayer({
  source: new VectorSource({
    url: 'data/geojson/countries.geojson',
    format: new GeoJSON()
  })
});

var map = new Map({
  layers: [raster, vector],
  target: 'map',
  view: new View({
    center: [0, 0],
    zoom: 2
  })
});

var select = null; // ref to currently selected interaction

// select interaction working on "singleclick"
var selectSingleClick = new Select();

// select interaction working on "click"
var selectClick = new Select({
  condition: click
});

// select interaction working on "pointermove"
var selectPointerMove = new Select({
  condition: pointerMove
});

var selectAltClick = new Select({
  condition: function(mapBrowserEvent) {
    return click(mapBrowserEvent) && altKeyOnly(mapBrowserEvent);
  }
});

var selectElement = document.getElementById('type');

/**
 * onchange callback on the select element.
 */
selectElement.onchange = changeInteraction;
changeInteraction();

<!DOCTYPE html>
<html>
  <head>
    <title>Select Features</title>
    <link rel="stylesheet" href="https://openlayers.org/en/v5.3.0/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>

  </head>
  <body>
    <div id="map" class="map"></div>
    <form class="form-inline">
      <label>Action type &nbsp;</label>
        <select id="type" class="form-control">
          <option value="click" selected>Click</option>
          <option value="singleclick">Single-click</option>
          <option value="pointermove">Hover</option>
          <option value="altclick">Alt+Click</option>
          <option value="none">None</option>
        </select>
      <span id="status">&nbsp;0 selected features</span>
    </form>
    <script>
      import Map from 'ol/Map.js';
      import View from 'ol/View.js';
      import {click, pointerMove, altKeyOnly} from 'ol/events/condition.js';
      import GeoJSON from 'ol/format/GeoJSON.js';
      import Select from 'ol/interaction/Select.js';
      import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer.js';
      import OSM from 'ol/source/OSM.js';
      import VectorSource from 'ol/source/Vector.js';

      var raster = new TileLayer({
        source: new OSM()
      });

      var vector = new VectorLayer({
        source: new VectorSource({
          url: 'data/geojson/countries.geojson',
          format: new GeoJSON()
        })
      });

      var map = new Map({
        layers: [raster, vector],
        target: 'map',
        view: new View({
          center: [0, 0],
          zoom: 2
        })
      });

      var select = null; // ref to currently selected interaction

      // select interaction working on "singleclick"
      var selectSingleClick = new Select();

      // select interaction working on "click"
      var selectClick = new Select({
        condition: click
      });

      // select interaction working on "pointermove"
      var selectPointerMove = new Select({
        condition: pointerMove
      });

      var selectAltClick = new Select({
        condition: function(mapBrowserEvent) {
          return click(mapBrowserEvent) && altKeyOnly(mapBrowserEvent);
        }
      });

      var selectElement = document.getElementById('type');

      var changeInteraction = function() {
        if (select !== null) {
          map.removeInteraction(select);
        }
        var value = selectElement.value;
        if (value == 'singleclick') {
          select = selectSingleClick;
        } else if (value == 'click') {
          select = selectClick;
        } else if (value == 'pointermove') {
          select = selectPointerMove;
        } else if (value == 'altclick') {
          select = selectAltClick;
        } else {
          select = null;
        }
        if (select !== null) {
          map.addInteraction(select);
          select.on('select', function(e) {
            document.getElementById('status').innerHTML = '&nbsp;' +
                e.target.getFeatures().getLength() +
                ' selected features (last operation selected ' + e.selected.length +
                ' and deselected ' + e.deselected.length + ' features)';
          });
        }
      };


      /**
       * onchange callback on the select element.
       */
      selectElement.onchange = changeInteraction;
      changeInteraction();
    </script>
  </body>
</html>