title: amcharts drill-down map countries clickable
body: <p>The drill-down map example has the <code>index.html</code> file which references three relevant javascript files.</p>
  
  <ol>
  <li>index.js</li>
  <li>continentsLow.js</li>
  <li>worldLow.js</li>
  </ol>
  
  <p>Now various references point to the definition of an <a href="https://stackoverflow.com/questions/49307377/amcharts-interactive-map-making-selected-states-a-clickable-link#49361414">array of areas</a> that allow <a href="https://amcharts.zendesk.com/hc/en-us/articles/203002122-How-do-I-hyperlink-country-or-other-area-to-some-URL-" rel="nofollow noreferrer">url and target to be specified</a>.</p>
  
  <p>But it is not readily obvious which javascript file would carry this load.</p>
  
  <p>The relevant section of the index.js file to my eyes is:</p>
  
  <pre><code>// Countries
  var countriesSeries = chart.series.push(new am4maps.MapPolygonSeries());
  var countries = countriesSeries.mapPolygons;
  countriesSeries.visible = false; // start off as hidden
  countriesSeries.exclude = ["AQ"];
  countriesSeries.geodata = am4geodata_worldLow;
  countriesSeries.useGeodata = true;
  // Hide each country so we can fade them in
  countriesSeries.events.once("inited", function() {
    hideCountries();
  });
  </code></pre>
  
  <p>The <code>worldLow</code>file seems a more appropriate spot  as it defines the countries polygons</p>
  
  <pre><code>am4internal_webpackJsonp(["fcaa"],{ATzU:function(e,t,o){"use strict";Object.defineProperty(t,"__esModule",{value:!0});window.am4geodata_worldLow={type:"FeatureCollection",
  features:[{type:"Feature",geometry:{type:"Polygon",coordinates:[[[179.2223,-8.554],[179.2023,-8.4653],[179.2312,-8.5048],[179.2223,-8.554]]]},properties:{name:"Tuvalu",id:"TV"},id:"TV"},
  {type:"Feature",geometry:{type:"Polygon",coordinates:[[[3.4624,-54.4471],[3.3461,-54.4511],[3.3669,-54.3997],[3.4814,-54.4001],[3.4624,-54.4471]]]},properties:{name:"Bouvet Island",id:"BV"},id:"BV"},
  {type:"Feature",geometry:{type:"Polygon",coordinates:[[[-5.3345,36.1623],[-5.3382,36.1122],[-5.3562,36.1264],[-5.3551,36.1455],[-5.3345,36.1623]]]},[...]
  </code></pre>
  
  <p>while I attempted to add a <code>url</code> attribute in this array, it failed.</p>
  
  <p>What is the proper way to do this?</p>