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Select Features by Hover

Example of selecting features by hovering.

In this example, a listener is registered on the map's pointermove to highlight the currently hovered feature.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Select Features by Hover</title>
    <!-- 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>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <span id="status"></span>
    <script src="index.js"></script>
  </body>
</html>
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index.jsimport 'ol/ol.css';
import Map from 'ol/Map';
import View from 'ol/View';
import GeoJSON from 'ol/format/GeoJSON';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import OSM from 'ol/source/OSM';
import VectorSource from 'ol/source/Vector';
import Style from 'ol/style/Style';
import Fill from 'ol/style/Fill';
import Stroke from 'ol/style/Stroke';

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

var highlightStyle = new Style({
  fill: new Fill({
    color: 'rgba(255,255,255,0.7)'
  }),
  stroke: new Stroke({
    color: '#3399CC',
    width: 3
  })
});

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 selected = null;
var status = document.getElementById('status');

map.on('pointermove', function(e) {
  if (selected !== null) {
    selected.setStyle(undefined);
    selected = null;
  }

  map.forEachFeatureAtPixel(e.pixel, function(f) {
    selected = f;
    f.setStyle(highlightStyle);
    return true;
  });

  if (selected) {
    status.innerHTML = '&nbsp;Hovering: ' + selected.get('name');
  } else {
    status.innerHTML = '&nbsp;';
  }
});
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package.json{
  "name": "select-hover-features",
  "dependencies": {
    "ol": "6.1.1"
  },
  "devDependencies": {
    "parcel": "1.11.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --experimental-scope-hoisting --public-url . index.html"
  }
}