title: How to call a common function after both of the js files are loaded completely?
body: <p>I want to show markers on map in the form of clusters and for that purpose I am using "markercluster.js" and google maps v3 library. But the problem here is that to show markers on the map both the files should be loaded completely. One solution is that I load atleast one of the file synchronously but I want to load both the files using async and defer. Is there any way I can achieve both the things. Currently I am loading files in this way but when googleapi is loaded before markercluster then it start showing markerCluster as undefined inside initialize function. </p>
  
  <pre><code>&lt;script async defer src="js/markerclusterer.js"&gt;&lt;/script&gt;   
  &lt;script async defer src="//maps.googleapis.com/maps/api/js?v=3&amp;callback=initialize"&gt; &lt;/script&gt;
  </code></pre>