title: Find html label associated with a given input
body: <p>Let's say I have an html form.  Each input/select/textarea will have a corresponding <code>&lt;label&gt;</code> with the <code>for</code> attribute set to the id of it's companion. In this case, I know that each input will only have a single label.</p>
  
  <p>Given an input element in javascript &mdash; via an onkeyup event, for example &mdash; what's the best way to find it's associated label?</p>