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.

main.js

import 'ol/ol.css';
import Fill from 'ol/style/Fill';
import GeoJSON from 'ol/format/GeoJSON';
import Map from 'ol/Map';
import Stroke from 'ol/style/Stroke';
import Style from 'ol/style/Style';
import VectorLayer from 'ol/layer/Vector';
import VectorSource from 'ol/source/Vector';
import View from 'ol/View';

const style = new Style({
  fill: new Fill({
    color: '#eeeeee',
  }),
});

const vector = new VectorLayer({
  source: new VectorSource({
    url: 'https://openlayers.org/data/vector/ecoregions.json',
    format: new GeoJSON(),
  }),
  background: 'white',
  style: function (feature) {
    const color = feature.get('COLOR') || '#eeeeee';
    style.getFill().setColor(color);
    return style;
  },
});

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

const selectStyle = new Style({
  fill: new Fill({
    color: '#eeeeee',
  }),
  stroke: new Stroke({
    color: 'rgba(255, 255, 255, 0.7)',
    width: 2,
  }),
});

const status = document.getElementById('status');

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

  map.forEachFeatureAtPixel(e.pixel, function (f) {
    selected = f;
    selectStyle.getFill().setColor(f.get('COLOR') || '#eeeeee');
    f.setStyle(selectStyle);
    return true;
  });

  if (selected) {
    status.innerHTML = selected.get('ECO_NAME');
  } else {
    status.innerHTML = '&nbsp;';
  }
});

index.html

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>Select Features by Hover</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep@1.0.6/dist/elm-pep.js"></script>
    <!-- The lines below are only needed for old environments like Internet Explorer and Android 4.x -->
    <script src="https://cdn.polyfill.io/v3/polyfill.min.js?features=fetch,requestAnimationFrame,Element.prototype.classList,TextDecoder"></script>
    <script src="https://cdnjs.cloudflare.com/ajax/libs/core-js/3.18.3/minified.js"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <span id="status">&nbsp;</span>
    <script src="main.js"></script>
  </body>
</html>

package.json

{
  "name": "select-hover-features",
  "dependencies": {
    "ol": "6.13.1-dev"
  },
  "devDependencies": {
    "parcel": "^2.0.0"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}