asynchronous javascript loading/executing
<p>In this post, <a href="http://stackoverflow.com/questions/2774373/asynchronous-js-file-loading-syntax">asynchronous .js file loading syntax</a>, someone said, "If the async attribute is present, then the script will be executed asynchronously, as soon as it is available." </p>

<pre><code>(function() {
  var d=document,
  h=d.getElementsByTagName('head')[0],
  s=d.createElement('script');
  s.type='text/javascript';
  s.async=true;
  s.src='/js/myfile.js';
  h.appendChild(s);
}()); /* note ending parenthesis and curly brace */
</code></pre>

<p>My question is, what does "the script will be executed asynchronously" mean? Will this script be executed in a different thread from other javascripts in the page? If yes, should we worry about synchronization issue in the two threads?</p>

<p>Thanks.</p>
