Data Layer: Dynamic Styling

View this example full screen.

JavaScript

var map;
function initialize() {
  map = new google.maps.Map(document.getElementById('map-canvas'), {
    zoom: 4,
    center: {lat: -28, lng: 137.883}
  });

  // Load GeoJSON.
  map.data.loadGeoJson('https://storage.googleapis.com/maps-devrel/google.json');

  // Color each letter gray. Change the color when the isColorful property
  // is set to true.
  map.data.setStyle(function(feature) {
    var color = 'gray';
    if (feature.getProperty('isColorful')) {
      color = feature.getProperty('color');
    }
    return /** @type {google.maps.Data.StyleOptions} */({
      fillColor: color,
      strokeColor: color,
      strokeWeight: 2
    });
  });

  // When the user clicks, set 'isColorful', changing the color of the letters.
  map.data.addListener('click', function(event) {
    event.feature.setProperty('isColorful', true);
  });

  // When the user hovers, tempt them to click by outlining the letters.
  // Call revertStyle() to remove all overrides. This will use the style rules
  // defined in the function passed to setStyle()
  map.data.addListener('mouseover', function(event) {
    map.data.revertStyle();
    map.data.overrideStyle(event.feature, {strokeWeight: 8});
  });

  map.data.addListener('mouseout', function(event) {
    map.data.revertStyle();
  });
}

google.maps.event.addDomListener(window, 'load', initialize);

JavaScript + HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Data Layer: Dynamic Styling</title>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <style>
      html, body, #map-canvas {
        height: 100%;
        margin: 0px;
        padding: 0px
      }
    </style>
    <script src="https://maps.googleapis.com/maps/api/js?v=3.exp&signed_in=true"></script>
    <script>
var map;
function initialize() {
  map = new google.maps.Map(document.getElementById('map-canvas'), {
    zoom: 4,
    center: {lat: -28, lng: 137.883}
  });

  // Load GeoJSON.
  map.data.loadGeoJson('https://storage.googleapis.com/maps-devrel/google.json');

  // [START snippet]
  // Color each letter gray. Change the color when the isColorful property
  // is set to true.
  map.data.setStyle(function(feature) {
    var color = 'gray';
    if (feature.getProperty('isColorful')) {
      color = feature.getProperty('color');
    }
    return /** @type {google.maps.Data.StyleOptions} */({
      fillColor: color,
      strokeColor: color,
      strokeWeight: 2
    });
  });

  // When the user clicks, set 'isColorful', changing the color of the letters.
  map.data.addListener('click', function(event) {
    event.feature.setProperty('isColorful', true);
  });

  // When the user hovers, tempt them to click by outlining the letters.
  // Call revertStyle() to remove all overrides. This will use the style rules
  // defined in the function passed to setStyle()
  map.data.addListener('mouseover', function(event) {
    map.data.revertStyle();
    map.data.overrideStyle(event.feature, {strokeWeight: 8});
  });

  map.data.addListener('mouseout', function(event) {
    map.data.revertStyle();
  });
  // [END snippet]
}

google.maps.event.addDomListener(window, 'load', initialize);

    </script>
  </head>
  <body>
    <div id="map-canvas"></div>
  </body>
</html>