best way to get the key of a key/value javascript object
<p>If I have a JS object like:</p>

<pre><code>var foo = { 'bar' : 'baz' }
</code></pre>

<p>If I know that <code>foo</code> has that basic key/value structure, but don't know the name of the key, what's the easiest way to get it? <code>for ... in</code>? <code>$.each()</code>? I hope there's something better....</p>
