Batterymap

<!DOCTYPE html>
<html>
  <head>
    <meta name="viewport" content="initial-scale=1.0, user-scalable=no">
    <meta charset="utf-8">
    <title>Batterymap</title>
    <style>
      html, body {
        height: 100%;
        margin: 0;
        padding: 0;
      }
      #map {
        height: 100%;
      }
    </style>
  </head>
  <body>
    <div id="map"></div>
    <script>
      function initMap() {
        var directionsService = new google.maps.DirectionsService;
        var map = new google.maps.Map(document.getElementById('map'), {
          zoom: 12,
          center: {lat: 40.790278, lng: -73.959722}
        });
        var infoWindow = new google.maps.InfoWindow({map: map});
        var destWindow = new google.maps.InfoWindow({map: map});

// Try HTML5 geolocation.
        if (navigator.geolocation) {
          navigator.geolocation.getCurrentPosition(function(position) {
            var pos = {
              lat: position.coords.latitude,
              lng: position.coords.longitude
            };

infoWindow.setPosition(pos);
            infoWindow.setContent('From here, battery will lose…');

destWindow.setPosition(pos)
            destWindow.setContent('Drag map to destination')

map.setCenter(pos);

var timeout;
            map.addListener('center_changed', function() {
              clearTimeout(timeout)
              timeout = window.setTimeout(update, 500);
            });

function update() {
              var goTo = map.getCenter().toJSON();

var driving,
                  transit,
                  walking;

var modes = {'DRIVING': undefined, 'TRANSIT': undefined, 'WALKING': undefined};

Object.keys(modes).forEach(function(mode) {
                getDistance(directionsService, pos, goTo, mode, function(time) {
                  modes[mode] = time;
                  render();
                });
              })

function render() {
                var html = Object.keys(modes).map(function(mode) {
                  return getBatteryFromTime(modes[mode]) + ' ' + mode.toLowerCase()
                }).join('<br/>')

// destWindow.open();
                destWindow.setPosition(goTo);
                destWindow.setContent(html);
                destWindow.setZIndex(999);
              }
            }

}, function() {
            handleLocationError(true, infoWindow, map.getCenter());
          });
        } else {
          // Browser doesn't support Geolocation
          handleLocationError(false, infoWindow, map.getCenter());
        }

}

function handleLocationError(browserHasGeolocation, infoWindow, pos) {
        infoWindow.setPosition(pos);
        infoWindow.setContent(browserHasGeolocation ?
                              'Error: The Geolocation service failed.' :
                              'Error: Your browser doesn\'t support geolocation.');
      }

function getBatteryFromTime(seconds) {
        if(!seconds) return "?"
        var iPhone7BatteryLifeInSeconds = 615 * 60;
        return Math.round((seconds / iPhone7BatteryLifeInSeconds) * 100) + '%';
      }

</script>
    <script async defer
    src="https://maps.googleapis.com/maps/api/js?key=AIzaSyCHQK4s3qUUwAF5ADAoZ-qDoDMeg7Noso4&callback=initMap">
    </script>
  </body>
</html>