What is the difference between "undefined" and undefined?
<p>I'm trying this quiz in the Chrome console: <a href="http://perfectionkills.com/javascript-quiz/" rel="nofollow">Quiz</a></p>

<p>I can explain most of them somewhat after trying them out. But one thing confuses me:</p>

<pre><code>var x = [typeof x, typeof y][1];
    typeof typeof x;
</code></pre>

<p>.... returns "string", which doesn't make any sense to me. </p>

<pre><code>var x = [typeof x, typeof y][1]; 
</code></pre>

<p>returns "undefined" </p>

<p><code>typeof "undefined"</code> </p>

<p>returns "string", which makes some sense because undefined was in quotes. But overall, I don't see the purpose of "undefined" in coexistance with undefined. Also, what kind of array syntax is that? "Javascript The Good Parts" says that there are no multidimensional arrays.</p>
