Circles

This example creates circles on the map, representing populations in North America.

TypeScript

// This example creates circles on the map, representing populations in North
// America.

// First, create an object containing LatLng and population for each city.

interface City {
  center: google.maps.LatLngLiteral;
  population: number;
}

const citymap: Record<string, City> = {
  chicago: {
    center: { lat: 41.878, lng: -87.629 },
    population: 2714856,
  },
  newyork: {
    center: { lat: 40.714, lng: -74.005 },
    population: 8405837,
  },
  losangeles: {
    center: { lat: 34.052, lng: -118.243 },
    population: 3857799,
  },
  vancouver: {
    center: { lat: 49.25, lng: -123.1 },
    population: 603502,
  },
};

function initMap(): void {
  // Create the map.
  const map = new google.maps.Map(
    document.getElementById("map") as HTMLElement,
    {
      zoom: 4,
      center: { lat: 37.09, lng: -95.712 },
      mapTypeId: "terrain",
    }
  );

  // Construct the circle for each value in citymap.
  // Note: We scale the area of the circle based on the population.
  for (const city in citymap) {
    // Add the circle for this city to the map.
    const cityCircle = new google.maps.Circle({
      strokeColor: "#FF0000",
      strokeOpacity: 0.8,
      strokeWeight: 2,
      fillColor: "#FF0000",
      fillOpacity: 0.35,
      map,
      center: citymap[city].center,
      radius: Math.sqrt(citymap[city].population) * 100,
    });
  }
}index.ts

JavaScript

const citymap = {
  chicago: {
    center: { lat: 41.878, lng: -87.629 },
    population: 2714856,
  },
  newyork: {
    center: { lat: 40.714, lng: -74.005 },
    population: 8405837,
  },
  losangeles: {
    center: { lat: 34.052, lng: -118.243 },
    population: 3857799,
  },
  vancouver: {
    center: { lat: 49.25, lng: -123.1 },
    population: 603502,
  },
};

function initMap() {
  // Create the map.
  const map = new google.maps.Map(document.getElementById("map"), {
    zoom: 4,
    center: { lat: 37.09, lng: -95.712 },
    mapTypeId: "terrain",
  });

  // Construct the circle for each value in citymap.
  // Note: We scale the area of the circle based on the population.
  for (const city in citymap) {
    // Add the circle for this city to the map.
    const cityCircle = new google.maps.Circle({
      strokeColor: "#FF0000",
      strokeOpacity: 0.8,
      strokeWeight: 2,
      fillColor: "#FF0000",
      fillOpacity: 0.35,
      map,
      center: citymap[city].center,
      radius: Math.sqrt(citymap[city].population) * 100,
    });
  }
}
index.js

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.css

HTML

<!DOCTYPE html>
<html>
  <head>
    <title>Circles</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>

    <!-- 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>sample.html

All

<!DOCTYPE html>
<html>
  <head>
    <title>Circles</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;
      }
    </style>
    <script>
      const citymap = {
        chicago: {
          center: { lat: 41.878, lng: -87.629 },
          population: 2714856,
        },
        newyork: {
          center: { lat: 40.714, lng: -74.005 },
          population: 8405837,
        },
        losangeles: {
          center: { lat: 34.052, lng: -118.243 },
          population: 3857799,
        },
        vancouver: {
          center: { lat: 49.25, lng: -123.1 },
          population: 603502,
        },
      };

      function initMap() {
        // Create the map.
        const map = new google.maps.Map(document.getElementById("map"), {
          zoom: 4,
          center: { lat: 37.09, lng: -95.712 },
          mapTypeId: "terrain",
        });

        // Construct the circle for each value in citymap.
        // Note: We scale the area of the circle based on the population.
        for (const city in citymap) {
          // Add the circle for this city to the map.
          const cityCircle = new google.maps.Circle({
            strokeColor: "#FF0000",
            strokeOpacity: 0.8,
            strokeWeight: 2,
            fillColor: "#FF0000",
            fillOpacity: 0.35,
            map,
            center: citymap[city].center,
            radius: Math.sqrt(citymap[city].population) * 100,
          });
        }
      }
    </script>
  </head>
  <body>
    <div id="map"></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>
inline.html

/* 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>Circles</title> <script src="https://polyfill.io/v3/polyfill.min.js?features=default"></script>  </head> <body> <div id="map"></div>  <script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyBIwzALxUPNbatRBj3Xi1Uhp0fFzwWNBkE&callback=initMap&libraries=&v=weekly" async ></script> </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 circle-simple DESTINATION_FOLDER

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