What does this jQuery line do?
<p>I have a line of jQuery code that is causing an error as I placed two periods in front of the b class. I am wondering how does jQuery interpret the following line? If I had only one period in front of b instead of two, I assume that jQuery interpret it as: "if class b exists within class a which exists in the parent of this, alert prompt hi".</p>

<pre><code>if ( $(this).parent().find(".a ..b") ) {
  alert("hi");
});
</code></pre>
