Show drawn polygon area

Use Leaflet.draw to draw a polygon and leaflet-geodesy to calculate its area in square meters.

<!DOCTYPE html>
<html>
<head>
<meta charset=utf-8 />
<title>Show drawn polygon area</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src='https://api.mapbox.com/mapbox.js/v3.1.0/mapbox.js'></script>
<link href='https://api.mapbox.com/mapbox.js/v3.1.0/mapbox.css' rel='stylesheet' />
<style>
  body { margin:0; padding:0; }
  #map { position:absolute; top:0; bottom:0; width:100%; }
</style>
</head>
<body>
<link href='https://api.mapbox.com/mapbox.js/plugins/leaflet-draw/v0.2.3/leaflet.draw.css' rel='stylesheet' />
<script src='https://api.mapbox.com/mapbox.js/plugins/leaflet-draw/v0.2.3/leaflet.draw.js'></script>
<script src='https://api.mapbox.com/mapbox.js/plugins/leaflet-geodesy/v0.1.0/leaflet-geodesy.js'></script>

<div id='map'></div>

<script>
L.mapbox.accessToken = '<your access token here>';
var map = L.mapbox.map('map', 'mapbox.streets')
    .setView([38.89399, -77.03659], 17);

var featureGroup = L.featureGroup().addTo(map);

var drawControl = new L.Control.Draw({
  edit: {
    featureGroup: featureGroup
  },
  draw: {
    polygon: true,
    polyline: false,
    rectangle: false,
    circle: false,
    marker: false
  }
}).addTo(map);

map.on('draw:created', showPolygonArea);
map.on('draw:edited', showPolygonAreaEdited);

function showPolygonAreaEdited(e) {
  e.layers.eachLayer(function(layer) {
    showPolygonArea({ layer: layer });
  });
}
function showPolygonArea(e) {
  featureGroup.clearLayers();
  featureGroup.addLayer(e.layer);
  e.layer.bindPopup((LGeo.area(e.layer) / 1000000).toFixed(2) + ' km<sup>2</sup>');
  e.layer.openPopup();
}
</script>
to create your own custom map and use it in this example.
Use this example by copying its source into your own HTML page and replacing the Map ID with one of your own from your projects. Having trouble with JavaScript? Try out Codecademy or contact our support team.
Copy example