title: Is getElementByClass safe to use across browsers like getElementById?
body: <p>Is getElementByClass safe to use across browsers like getElementById?</p>
  
  <p><b>Update</b>
  Currently using:</p>
  
  <pre><code> window.opener.document.getElementById
  </code></pre>
  
  <p>But I want to reference the object by classname (there will be only 1 element with that classname).</p>