You're all set!

To start developing, please head over to our developer documentation.

Activate the Google Maps JavaScript API

To get you started we'll guide you through the Google Developers Console to do a few things first:

  1. Create or choose a project
  2. Activate the Google Maps JavaScript API and related services
  3. Create appropriate keys
Continue

Navigation functions (heading)

Read the documentation or view this example full screen.

// This example requires the Geometry library. Include the libraries=geometry
// parameter when you first load the API. For example:
// <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry">

var marker1, marker2;
var poly, geodesicPoly;

function initMap() {
  var map = new google.maps.Map(document.getElementById('map'), {
    zoom: 4,
    center: {lat: 34, lng: -40.605}
  });

  map.controls[google.maps.ControlPosition.TOP_CENTER].push(
      document.getElementById('info'));

  marker1 = new google.maps.Marker({
    map: map,
    draggable: true,
    position: {lat: 40.714, lng: -74.006}
  });

  marker2 = new google.maps.Marker({
    map: map,
    draggable: true,
    position: {lat: 48.857, lng: 2.352}
  });

  var bounds = new google.maps.LatLngBounds(
      marker1.getPosition(), marker2.getPosition());
  map.fitBounds(bounds);

  google.maps.event.addListener(marker1, 'position_changed', update);
  google.maps.event.addListener(marker2, 'position_changed', update);

  poly = new google.maps.Polyline({
    strokeColor: '#FF0000',
    strokeOpacity: 1.0,
    strokeWeight: 3,
    map: map,
  });

  geodesicPoly = new google.maps.Polyline({
    strokeColor: '#CC0099',
    strokeOpacity: 1.0,
    strokeWeight: 3,
    geodesic: true,
    map: map
  });

  update();
}

function update() {
  var path = [marker1.getPosition(), marker2.getPosition()];
  poly.setPath(path);
  geodesicPoly.setPath(path);
  var heading = google.maps.geometry.spherical.computeHeading(path[0], path[1]);
  document.getElementById('heading').value = heading;
  document.getElementById('origin').value = path[0].toString();
  document.getElementById('destination').value = path[1].toString();
}
<div id="map"></div>
<div id="floating-panel">
  Origin: <input type="text" readonly id="origin">
  Destination: <input type="text" readonly id="destination"><br>
  Heading: <input type="text" readonly id="heading"> degrees
</div>
html, body {
  height: 100%;
  margin: 0;
  padding: 0;
}
#map {
  height: 100%;
}
#floating-panel {
  position: absolute;
  top: 10px;
  left: 25%;
  z-index: 5;
  background-color: #fff;
  padding: 5px;
  border: 1px solid #999;
  text-align: center;
  font-family: 'Roboto','sans-serif';
  line-height: 30px;
  padding-left: 10px;
}
<!-- Replace the value of the key parameter with your own API key. -->
<script src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCkUOdZ5y7hMm0yrcCQoCvLwzdM6M8s5qk&libraries=geometry&callback=initMap"
        async defer></script>

Try it yourself

Hover at top right of the code block to copy the code or open it in JSFiddle.

<!DOCTYPE html>
<html>
  <head>
    <title>Navigation functions (heading)</title>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <style>
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
      #map {
        height: 100%;
      }
      #floating-panel {
        position: absolute;
        top: 10px;
        left: 25%;
        z-index: 5;
        background-color: #fff;
        padding: 5px;
        border: 1px solid #999;
        text-align: center;
        font-family: 'Roboto','sans-serif';
        line-height: 30px;
        padding-left: 10px;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
    <div id="floating-panel">
      Origin: <input type="text" readonly id="origin">
      Destination: <input type="text" readonly id="destination"><br>
      Heading: <input type="text" readonly id="heading"> degrees
    </div>
    <script>
      // This example requires the Geometry library. Include the libraries=geometry
      // parameter when you first load the API. For example:
      // <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry">

      var marker1, marker2;
      var poly, geodesicPoly;

      function initMap() {
        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 4,
          center: {lat: 34, lng: -40.605}
        });

        map.controls[google.maps.ControlPosition.TOP_CENTER].push(
            document.getElementById('info'));

        marker1 = new google.maps.Marker({
          map: map,
          draggable: true,
          position: {lat: 40.714, lng: -74.006}
        });

        marker2 = new google.maps.Marker({
          map: map,
          draggable: true,
          position: {lat: 48.857, lng: 2.352}
        });

        var bounds = new google.maps.LatLngBounds(
            marker1.getPosition(), marker2.getPosition());
        map.fitBounds(bounds);

        google.maps.event.addListener(marker1, 'position_changed', update);
        google.maps.event.addListener(marker2, 'position_changed', update);

        poly = new google.maps.Polyline({
          strokeColor: '#FF0000',
          strokeOpacity: 1.0,
          strokeWeight: 3,
          map: map,
        });

        geodesicPoly = new google.maps.Polyline({
          strokeColor: '#CC0099',
          strokeOpacity: 1.0,
          strokeWeight: 3,
          geodesic: true,
          map: map
        });

        update();
      }

      function update() {
        var path = [marker1.getPosition(), marker2.getPosition()];
        poly.setPath(path);
        geodesicPoly.setPath(path);
        var heading = google.maps.geometry.spherical.computeHeading(path[0], path[1]);
        document.getElementById('heading').value = heading;
        document.getElementById('origin').value = path[0].toString();
        document.getElementById('destination').value = path[1].toString();
      }
    </script>
    <script src="https://maps.googleapis.com/maps/api/js?key=YOUR_API_KEY&libraries=geometry&callback=initMap"
        async defer></script>
  </body>
</html>

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