title: Javascript Object - Key beginning with number, allowed?
body: <p>Is this allowed?</p>
  
  <pre><code>myObj = {};
  myObj['4a56546s6d']
  </code></pre>
  
  <p>Or the key must start with a letter like:</p>
  
  <pre><code>myObj = {};
  myObj['x4a56546s6d']
  </code></pre>
  
  <p>Can I mix both like:</p>
  
  <pre><code>myObj = {};
  myObj['x4a56546s6d']
  myObj['4a56546s6d']
  </code></pre>
  
  <p>I ask that because somethings (for example an ID in HTML) must begin with a letter. I have at the moment the <a href="https://i.stack.imgur.com/roLWA.png" rel="noreferrer">third version</a> and the fireBug marks the keys (beginning with a number) blue.</p>