It's the 15th anniversary of Google Maps Platform - Check out the latest news and announcements

Data Layer: Dynamic Styling

This example uses a data layer to dynamically change the appearance of some [KML feature objects[(/maps/documentation/javascript/kmllayer#kml_feature_details) when the user hovers over or clicks them.

Read the documentation.

TypeScript

let map: google.maps.Map;

function initMap(): void {
  map = new google.maps.Map(document.getElementById("map") as HTMLElement, {
    zoom: 4,
    center: { lat: -28, lng: 137 }
  });

  // Load GeoJSON.
  map.data.loadGeoJson(
    "https://storage.googleapis.com/mapsdevsite/json/google.json"
  );

  // Color each letter gray. Change the color when the isColorful property
  // is set to true.
  map.data.setStyle(feature => {
    let 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", 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", event => {
    map.data.revertStyle();
    map.data.overrideStyle(event.feature, { strokeWeight: 8 });
  });

  map.data.addListener("mouseout", event => {
    map.data.revertStyle();
  });
}

JavaScript

let map;

function initMap() {
  map = new google.maps.Map(document.getElementById("map"), {
    zoom: 4,
    center: { lat: -28, lng: 137 }
  });
  // Load GeoJSON.
  map.data.loadGeoJson(
    "https://storage.googleapis.com/mapsdevsite/json/google.json"
  );
  // Color each letter gray. Change the color when the isColorful property
  // is set to true.
  map.data.setStyle(feature => {
    let 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", 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", event => {
    map.data.revertStyle();
    map.data.overrideStyle(event.feature, { strokeWeight: 8 });
  });
  map.data.addListener("mouseout", event => {
    map.data.revertStyle();
  });
}

CSS

/* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
#map {
  height: 100%;
}

/* Optional: Makes the sample page fill the window. */
html,
body {
  height: 100%;
  margin: 0;
  padding: 0;
}

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Data Layer: Dynamic Styling</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <script
      src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap&libraries=&v=weekly"
      defer
    ></script>
    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script src="./app.js"></script>
  </head>
  <body>
    <div id="map"></div>
  </body>
</html>

All

<!DOCTYPE html>
<html>
  <head>
    <title>Data Layer: Dynamic Styling</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <script
      src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap&libraries=&v=weekly"
      defer
    ></script>
    <style type="text/css">
      /* Always set the map height explicitly to define the size of the div
       * element that contains the map. */
      #map {
        height: 100%;
      }

      /* Optional: Makes the sample page fill the window. */
      html,
      body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
    </style>
    <script>
      "use strict";

      let map;

      function initMap() {
        map = new google.maps.Map(document.getElementById("map"), {
          zoom: 4,
          center: {
            lat: -28,
            lng: 137
          }
        }); // Load GeoJSON.

        map.data.loadGeoJson(
          "https://storage.googleapis.com/mapsdevsite/json/google.json"
        ); // Color each letter gray. Change the color when the isColorful property
        // is set to true.

        map.data.setStyle(feature => {
          let 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", 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", event => {
          map.data.revertStyle();
          map.data.overrideStyle(event.feature, {
            strokeWeight: 8
          });
        });
        map.data.addListener("mouseout", event => {
          map.data.revertStyle();
        });
      }
    </script>
  </head>
  <body>
    <div id="map"></div>
  </body>
</html>
"use strict"; let map; function initMap() { map = new google.maps.Map(document.getElementById("map"), { zoom: 4, center: { lat: -28, lng: 137 } }); // Load GeoJSON. map.data.loadGeoJson( "https://storage.googleapis.com/mapsdevsite/json/google.json" ); // Color each letter gray. Change the color when the isColorful property // is set to true. map.data.setStyle(feature => { let 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", 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", event => { map.data.revertStyle(); map.data.overrideStyle(event.feature, { strokeWeight: 8 }); }); map.data.addListener("mouseout", event => { map.data.revertStyle(); }); }
/* Always set the map height explicitly to define the size of the div * element that contains the map. */ #map { height: 100%; } /* Optional: Makes the sample page fill the window. */ html, body { height: 100%; margin: 0; padding: 0; }
<!DOCTYPE html> <html> <head> <title>Data Layer: Dynamic Styling</title> <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCb1xprYSpXd0q_yDsJ1W2UGhfl9_YGKU0&callback=initMap&libraries=&v=weekly" defer ></script> <!-- jsFiddle will insert css and js --> </head> <body> <div id="map"></div> </body> </html>