<!DOCTYPE html>
<meta charset='utf-8' />
<title>Draw Polygons</title>
<meta name='viewport' content='initial-scale=1,maximum-scale=1,user-scalable=no' />
<script src='https://api.mapbox.com/mapbox-gl-js/v1.8.0/mapbox-gl.js'></script>
<link href='https://api.mapbox.com/mapbox-gl-js/v1.8.0/mapbox-gl.css' rel='stylesheet' />

<script src='https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.0.0/mapbox-gl-draw.js'></script>
<link rel='stylesheet' href='https://api.mapbox.com/mapbox-gl-js/plugins/mapbox-gl-draw/v1.0.0/mapbox-gl-draw.css' type='text/css' />
            body { margin:0px; padding:0px; }
            #map { position:absolute; top:0px; bottom:0px; width:100%; }
<div id='map'></div>
            //Add your LocationIQ Maps Access Token here (not the API token!)
            locationiqKey = 'pk.a5c3fbf2119bfb2275b62eddbccd76b3';
            //Define the map and configure the map's theme
            var map = new mapboxgl.Map({
                container: 'map',
                attributionControl: false, //need this to show a compact attribution icon (i) instead of the whole text
                style: 'https://tiles.locationiq.com/v3/streets/vector.json?key='+locationiqKey,
                zoom: 12,
                center: [-122.42, 37.779]

            //Add draw controls
            var draw = new MapboxDraw({
               displayControlsDefault: false,
               controls: {
                   polygon: true,
                   trash: true

            //Add listeners
            map.on('draw.create', updateArea);
            map.on('draw.delete', updateArea);
            map.on('draw.update', updateArea);

            //This function is called when a draw event is triggered (create, delete, update)
            //API ref for all that you can do with the draw control: https://github.com/mapbox/mapbox-gl-draw/blob/master/docs/API.md
            function updateArea(e) {
                var data = draw.getAll();
                //We are simply logging all the geometries into console
                //Your first shape's points data can be found in features->0->geometry->coordinates
                //You can use http://turfjs.org/ to get bounding boxes, area, etc for these shapes