Is there anything wrong with using 'var undefined' to test for undefined
<p>Is there anything wrong with this test for undefined?</p>

<pre><code>var undefined;

if(x == undefined){
    //do something
}
</code></pre>

<p>or this:</p>

<pre><code>function undefined(x){
    return typeof x == 'undefined';
}

if(undefined(x)){
    //do something
}
</code></pre>

<p>jsLint doesn't throws a reserverd word error, but the code still seems to work...</p>
