Data Layer: Event Handling

This example uses a data layer to dynamically display information about a KML feature object when under the mouse cursor.

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/maps-devrel/google.json"
  );

  // Add some style.
  map.data.setStyle((feature) => {
    return /** @type {google.maps.Data.StyleOptions} */ {
      fillColor: feature.getProperty("color"),
      strokeWeight: 1,
    };
  });

  // Set mouseover event for each feature.
  map.data.addListener("mouseover", (event) => {
    (document.getElementById(
      "info-box"
    ) as HTMLElement).textContent = event.feature.getProperty("letter");
  });
}

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/maps-devrel/google.json"
  );
  // Add some style.
  map.data.setStyle((feature) => {
    return /** @type {google.maps.Data.StyleOptions} */ {
      fillColor: feature.getProperty("color"),
      strokeWeight: 1,
    };
  });
  // Set mouseover event for each feature.
  map.data.addListener("mouseover", (event) => {
    document.getElementById("info-box").textContent = event.feature.getProperty(
      "letter"
    );
  });
}

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;
}

#info-box {
  background-color: white;
  border: 1px solid black;
  bottom: 30px;
  height: 20px;
  padding: 10px;
  position: absolute;
  left: 30px;
}

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Data Layer: Event Handling</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="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>
    <div id="info-box">?</div>
  </body>
</html>

All

<!DOCTYPE html>
<html>
  <head>
    <title>Data Layer: Event Handling</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;
      }

      #info-box {
        background-color: white;
        border: 1px solid black;
        bottom: 30px;
        height: 20px;
        padding: 10px;
        position: absolute;
        left: 30px;
      }
    </style>
    <script>
      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/maps-devrel/google.json"
        );
        // Add some style.
        map.data.setStyle((feature) => {
          return /** @type {google.maps.Data.StyleOptions} */ {
            fillColor: feature.getProperty("color"),
            strokeWeight: 1,
          };
        });
        // Set mouseover event for each feature.
        map.data.addListener("mouseover", (event) => {
          document.getElementById(
            "info-box"
          ).textContent = event.feature.getProperty("letter");
        });
      }
    </script>
  </head>
  <body>
    <div id="map"></div>
    <div id="info-box">?</div>
  </body>
</html>
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/maps-devrel/google.json" ); // Add some style. map.data.setStyle((feature) => { return /** @type {google.maps.Data.StyleOptions} */ { fillColor: feature.getProperty("color"), strokeWeight: 1, }; }); // Set mouseover event for each feature. map.data.addListener("mouseover", (event) => { document.getElementById("info-box").textContent = event.feature.getProperty( "letter" ); }); }
/* 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; } #info-box { background-color: white; border: 1px solid black; bottom: 30px; height: 20px; padding: 10px; position: absolute; left: 30px; }
<!DOCTYPE html> <html> <head> <title>Data Layer: Event Handling</title> <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyBIwzALxUPNbatRBj3Xi1Uhp0fFzwWNBkE&callback=initMap&libraries=&v=weekly" defer ></script> <!-- jsFiddle will insert css and js --> </head> <body> <div id="map"></div> <div id="info-box">?</div> </body> </html>

Create a starter application from sample

A skeleton starter application using TypeScript, Webpack, and Babel can be generated from this sample using one of the methods below.

Run Locally

Node.js is required to run this sample locally. Follow these instructions to install Node.js and NPM.

npx @googlemaps/js-samples init layer-data-event DESTINATION_FOLDER

Run in Google Cloud Shell

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Run in Cloud Shell