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Earthquakes Heatmap

Demonstrates the use of a heatmap layer.

This example parses a KML file and renders the features as a ol/layer/Heatmap layer.

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index.html<!DOCTYPE html>
<html lang="en">
  <head>
    <title>Earthquakes Heatmap</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>
    <form>
      <label>radius size</label>
      <input id="radius" type="range" min="1" max="50" step="1" value="5"/>
      <label>blur size</label>
      <input id="blur" type="range" min="1" max="50" step="1" value="15"/>
    </form>
    <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 KML from 'ol/format/KML';
import {Heatmap as HeatmapLayer, Tile as TileLayer} from 'ol/layer';
import Stamen from 'ol/source/Stamen';
import VectorSource from 'ol/source/Vector';

var blur = document.getElementById('blur');
var radius = document.getElementById('radius');

var vector = new HeatmapLayer({
  source: new VectorSource({
    url: 'data/kml/2012_Earthquakes_Mag5.kml',
    format: new KML({
      extractStyles: false
    })
  }),
  blur: parseInt(blur.value, 10),
  radius: parseInt(radius.value, 10),
  weight: function(feature) {
    // 2012_Earthquakes_Mag5.kml stores the magnitude of each earthquake in a
    // standards-violating <magnitude> tag in each Placemark.  We extract it from
    // the Placemark's name instead.
    var name = feature.get('name');
    var magnitude = parseFloat(name.substr(2));
    return magnitude - 5;
  }
});

var raster = new TileLayer({
  source: new Stamen({
    layer: 'toner'
  })
});

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

var blurHandler = function() {
  vector.setBlur(parseInt(blur.value, 10));
};
blur.addEventListener('input', blurHandler);
blur.addEventListener('change', blurHandler);

var radiusHandler = function() {
  vector.setRadius(parseInt(radius.value, 10));
};
radius.addEventListener('input', radiusHandler);
radius.addEventListener('change', radiusHandler);
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package.json{
  "name": "heatmap-earthquakes",
  "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"
  }
}