Customizing a Google Map: Custom Legends

Overview

Learn how to create a legend on a Google map through this tutorial. Legends generally describe the symbols and markers on a map. You can create them using the positioning feature of custom controls.

The map below contains a legend that provides information about three different custom markers on the map.

The section below displays the entire code you need to create the map and legend in this tutorial.

TypeScript

let map: google.maps.Map;

function initMap(): void {
  map = new google.maps.Map(document.getElementById("map") as HTMLElement, {
    zoom: 16,
    center: new google.maps.LatLng(-33.91722, 151.23064),
    mapTypeId: "roadmap",
  });

  const iconBase = "https://maps.google.com/mapfiles/kml/shapes/";
  const icons: Record<string, any> = {
    parking: {
      name: "Parking",
      icon: iconBase + "parking_lot_maps.png",
    },
    library: {
      name: "Library",
      icon: iconBase + "library_maps.png",
    },
    info: {
      name: "Info",
      icon: iconBase + "info-i_maps.png",
    },
  };

  const features = [
    {
      position: new google.maps.LatLng(-33.91721, 151.2263),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91539, 151.2282),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91747, 151.22912),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.9191, 151.22907),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91725, 151.23011),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91872, 151.23089),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91784, 151.23094),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91682, 151.23149),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.9179, 151.23463),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91666, 151.23468),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.916988, 151.23364),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91662347903106, 151.22879464019775),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.916365282092855, 151.22937399734496),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91665018901448, 151.2282474695587),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.919543720969806, 151.23112279762267),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91608037421864, 151.23288232673644),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91851096391805, 151.2344058214569),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91818154739766, 151.2346203981781),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91727341958453, 151.23348314155578),
      type: "library",
    },
  ];

  features.forEach((feature) => {
    new google.maps.Marker({
      position: feature.position,
      icon: icons[feature.type].icon,
      map: map,
    });
  });

  const legend = document.getElementById("legend") as HTMLElement;

  for (const key in icons) {
    const type = icons[key];
    const name = type.name;
    const icon = type.icon;
    const div = document.createElement("div");
    div.innerHTML = '<img src="' + icon + '"> ' + name;
    legend.appendChild(div);
  }

  map.controls[google.maps.ControlPosition.RIGHT_BOTTOM].push(legend);
}

JavaScript

let map;

function initMap() {
  map = new google.maps.Map(document.getElementById("map"), {
    zoom: 16,
    center: new google.maps.LatLng(-33.91722, 151.23064),
    mapTypeId: "roadmap",
  });
  const iconBase = "https://maps.google.com/mapfiles/kml/shapes/";
  const icons = {
    parking: {
      name: "Parking",
      icon: iconBase + "parking_lot_maps.png",
    },
    library: {
      name: "Library",
      icon: iconBase + "library_maps.png",
    },
    info: {
      name: "Info",
      icon: iconBase + "info-i_maps.png",
    },
  };
  const features = [
    {
      position: new google.maps.LatLng(-33.91721, 151.2263),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91539, 151.2282),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91747, 151.22912),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.9191, 151.22907),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91725, 151.23011),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91872, 151.23089),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91784, 151.23094),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91682, 151.23149),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.9179, 151.23463),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91666, 151.23468),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.916988, 151.23364),
      type: "info",
    },
    {
      position: new google.maps.LatLng(-33.91662347903106, 151.22879464019775),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.916365282092855, 151.22937399734496),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91665018901448, 151.2282474695587),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.919543720969806, 151.23112279762267),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91608037421864, 151.23288232673644),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91851096391805, 151.2344058214569),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91818154739766, 151.2346203981781),
      type: "parking",
    },
    {
      position: new google.maps.LatLng(-33.91727341958453, 151.23348314155578),
      type: "library",
    },
  ];
  features.forEach((feature) => {
    new google.maps.Marker({
      position: feature.position,
      icon: icons[feature.type].icon,
      map: map,
    });
  });
  const legend = document.getElementById("legend");

  for (const key in icons) {
    const type = icons[key];
    const name = type.name;
    const icon = type.icon;
    const div = document.createElement("div");
    div.innerHTML = '<img src="' + icon + '"> ' + name;
    legend.appendChild(div);
  }
  map.controls[google.maps.ControlPosition.RIGHT_BOTTOM].push(legend);
}

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;
}

#legend {
  font-family: Arial, sans-serif;
  background: #fff;
  padding: 10px;
  margin: 10px;
  border: 3px solid #000;
}

#legend h3 {
  margin-top: 0;
}

#legend img {
  vertical-align: middle;
}

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Custom Legend</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>
    <link rel="stylesheet" type="text/css" href="./style.css" />
    <script src="./index.js"></script>
  </head>
  <body>
    <div id="map"></div>
    <div id="legend"><h3>Legend</h3></div>

    <!-- Async script executes immediately and must be after any DOM elements used in callback. -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap&libraries=&v=weekly"
      async
    ></script>
  </body>
</html>

All

<!DOCTYPE html>
<html>
  <head>
    <title>Custom Legend</title>
    <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></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;
      }

      #legend {
        font-family: Arial, sans-serif;
        background: #fff;
        padding: 10px;
        margin: 10px;
        border: 3px solid #000;
      }

      #legend h3 {
        margin-top: 0;
      }

      #legend img {
        vertical-align: middle;
      }
    </style>
    <script>
      let map;

      function initMap() {
        map = new google.maps.Map(document.getElementById("map"), {
          zoom: 16,
          center: new google.maps.LatLng(-33.91722, 151.23064),
          mapTypeId: "roadmap",
        });
        const iconBase = "https://maps.google.com/mapfiles/kml/shapes/";
        const icons = {
          parking: {
            name: "Parking",
            icon: iconBase + "parking_lot_maps.png",
          },
          library: {
            name: "Library",
            icon: iconBase + "library_maps.png",
          },
          info: {
            name: "Info",
            icon: iconBase + "info-i_maps.png",
          },
        };
        const features = [
          {
            position: new google.maps.LatLng(-33.91721, 151.2263),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.91539, 151.2282),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.91747, 151.22912),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.9191, 151.22907),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.91725, 151.23011),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.91872, 151.23089),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.91784, 151.23094),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.91682, 151.23149),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.9179, 151.23463),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.91666, 151.23468),
            type: "info",
          },
          {
            position: new google.maps.LatLng(-33.916988, 151.23364),
            type: "info",
          },
          {
            position: new google.maps.LatLng(
              -33.91662347903106,
              151.22879464019775
            ),
            type: "parking",
          },
          {
            position: new google.maps.LatLng(
              -33.916365282092855,
              151.22937399734496
            ),
            type: "parking",
          },
          {
            position: new google.maps.LatLng(
              -33.91665018901448,
              151.2282474695587
            ),
            type: "parking",
          },
          {
            position: new google.maps.LatLng(
              -33.919543720969806,
              151.23112279762267
            ),
            type: "parking",
          },
          {
            position: new google.maps.LatLng(
              -33.91608037421864,
              151.23288232673644
            ),
            type: "parking",
          },
          {
            position: new google.maps.LatLng(
              -33.91851096391805,
              151.2344058214569
            ),
            type: "parking",
          },
          {
            position: new google.maps.LatLng(
              -33.91818154739766,
              151.2346203981781
            ),
            type: "parking",
          },
          {
            position: new google.maps.LatLng(
              -33.91727341958453,
              151.23348314155578
            ),
            type: "library",
          },
        ];
        features.forEach((feature) => {
          new google.maps.Marker({
            position: feature.position,
            icon: icons[feature.type].icon,
            map: map,
          });
        });
        const legend = document.getElementById("legend");

        for (const key in icons) {
          const type = icons[key];
          const name = type.name;
          const icon = type.icon;
          const div = document.createElement("div");
          div.innerHTML = '<img src="' + icon + '"> ' + name;
          legend.appendChild(div);
        }
        map.controls[google.maps.ControlPosition.RIGHT_BOTTOM].push(legend);
      }
    </script>
  </head>
  <body>
    <div id="map"></div>
    <div id="legend"><h3>Legend</h3></div>

    <!-- Async script executes immediately and must be after any DOM elements used in callback. -->
    <script
      src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&callback=initMap&libraries=&v=weekly"
      async
    ></script>
  </body>
</html>
let map; function initMap() { map = new google.maps.Map(document.getElementById("map"), { zoom: 16, center: new google.maps.LatLng(-33.91722, 151.23064), mapTypeId: "roadmap", }); const iconBase = "https://maps.google.com/mapfiles/kml/shapes/"; const icons = { parking: { name: "Parking", icon: iconBase + "parking_lot_maps.png", }, library: { name: "Library", icon: iconBase + "library_maps.png", }, info: { name: "Info", icon: iconBase + "info-i_maps.png", }, }; const features = [ { position: new google.maps.LatLng(-33.91721, 151.2263), type: "info", }, { position: new google.maps.LatLng(-33.91539, 151.2282), type: "info", }, { position: new google.maps.LatLng(-33.91747, 151.22912), type: "info", }, { position: new google.maps.LatLng(-33.9191, 151.22907), type: "info", }, { position: new google.maps.LatLng(-33.91725, 151.23011), type: "info", }, { position: new google.maps.LatLng(-33.91872, 151.23089), type: "info", }, { position: new google.maps.LatLng(-33.91784, 151.23094), type: "info", }, { position: new google.maps.LatLng(-33.91682, 151.23149), type: "info", }, { position: new google.maps.LatLng(-33.9179, 151.23463), type: "info", }, { position: new google.maps.LatLng(-33.91666, 151.23468), type: "info", }, { position: new google.maps.LatLng(-33.916988, 151.23364), type: "info", }, { position: new google.maps.LatLng(-33.91662347903106, 151.22879464019775), type: "parking", }, { position: new google.maps.LatLng(-33.916365282092855, 151.22937399734496), type: "parking", }, { position: new google.maps.LatLng(-33.91665018901448, 151.2282474695587), type: "parking", }, { position: new google.maps.LatLng(-33.919543720969806, 151.23112279762267), type: "parking", }, { position: new google.maps.LatLng(-33.91608037421864, 151.23288232673644), type: "parking", }, { position: new google.maps.LatLng(-33.91851096391805, 151.2344058214569), type: "parking", }, { position: new google.maps.LatLng(-33.91818154739766, 151.2346203981781), type: "parking", }, { position: new google.maps.LatLng(-33.91727341958453, 151.23348314155578), type: "library", }, ]; features.forEach((feature) => { new google.maps.Marker({ position: feature.position, icon: icons[feature.type].icon, map: map, }); }); const legend = document.getElementById("legend"); for (const key in icons) { const type = icons[key]; const name = type.name; const icon = type.icon; const div = document.createElement("div"); div.innerHTML = '<img src="' + icon + '"> ' + name; legend.appendChild(div); } map.controls[google.maps.ControlPosition.RIGHT_BOTTOM].push(legend); }
/* 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; } #legend { font-family: Arial, sans-serif; background: #fff; padding: 10px; margin: 10px; border: 3px solid #000; } #legend h3 { margin-top: 0; } #legend img { vertical-align: middle; }
<!DOCTYPE html> <html> <head> <title>Custom Legend</title> <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script> <!-- jsFiddle will insert css and js --> </head> <body> <div id="map"></div> <div id="legend"><h3>Legend</h3></div> <!-- Async script executes immediately and must be after any DOM elements used in callback. --> <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyBIwzALxUPNbatRBj3Xi1Uhp0fFzwWNBkE&callback=initMap&libraries=&v=weekly" async ></script> </body> </html>

The sections below explain the main steps to create a legend.

Creating the legend container

The table below explains the code that customizes the legend.

Code and description
<div id="legend"><h3>Legend</h3></div>

Creates a div to hold the content.
Adds a heading level three (3) to the div.
map.controls[google.maps.ControlPosition.RIGHT_BOTTOM].push
(document.getElementById('legend'));

Positions the div at the right-bottom of the map by adding a control position.
Read about more control position options.
<style>
  #legend {
    font-family: Arial, sans-serif;
    background: #fff;
    padding: 10px;
    margin: 10px;
    border: 3px solid #000;
  }
</style>

Styles the legend control using CSS.

Adding the legend content

Use the existing marker styles definition to populate the legend.

var legend = document.getElementById('legend');
for (var style in styles) {
  var name = style.name;
  var icon = style.icon;
  var div = document.createElement('div');
  div.innerHTML = '<img src="' + icon + '"> ' + name;
  legend.appendChild(div);
}