jQuery `is` is not a function
<p>I have following HTML menu: </p>

<pre><code>&lt;ul&gt;
    &lt;li&gt;&lt;a href="index.html"&gt;Index Page&lt;/a&gt;&lt;/li&gt;
    &lt;li&gt;&lt;a href="#some-page"&gt;Some Page&lt;/a&gt;&lt;/li&gt;
&lt;/ul&gt;
</code></pre>

<p>Let say that <code>var url = "some-page";</code></p>

<pre><code>    $('#menu li a').prop('href')
                   .is('#' + url )
                   .parrent()
                   .addClass('active');
</code></pre>

<p>I'm keep getting error msg <code>.is is not a function</code>. Why? <code>.is</code> is clearly a function.</p>

<p>Any suggestion much appreciated.</p>
