typeof result of 2 undefined variable
<p>I just test the "typeof" in javascript, and really don't know why the result is like this. </p>

<p>/<strong><em>*</em>**<em>*</em></strong>/  </p>

<pre><code>var cota,
    plouto;

alert(typeof plouto/cota); //NaN 
</code></pre>

<p>/<strong><em>*</em>**<em>*</em></strong>/  </p>

<pre><code>var cota,
    plouto;

alert(typeof (plouto/cota)); //number
</code></pre>

<p>/<strong><em>*</em>**<em>*</em></strong>/      </p>

<pre><code>var cota,
    plouto;

var flo = plouto/cota;

alert(typeof flo); //number 
</code></pre>
