title: JavaScript: Does an async function create a new thread?
body: <p>Mozilla’s documentation on <code>XMLHttpRequest</code> includes the following on the <code>async</code> parameter:</p>
  
  <blockquote>
    <p>Note: Synchronous requests on the main thread can be easily disruptive to the user experience and should be avoided; in fact, many browsers have deprecated synchronous XHR support on the main thread entirely.</p>
  </blockquote>
  
  <p>That makes sense, as you don’t what to hold up the main thread waiting for an indeterminate period of time.</p>
  
  <p>If I create an <code>async</code> function which includes usng <code>XMLHttpRequest</code>, would that qualify as a new thread?</p>
  
  <p>I know about <code>fetch()</code>, I know about promises, and I know about using <code>XMLHttpRequest</code> with callbacks. This question is about the <code>async</code> keyword.</p>