Next parameter is 'undefined' in jQuery, why?
<p>In following code of <code>jQuery</code>, why next parameter is <code>undefined</code></p>

<p>JavaScript:</p>

<pre><code>(function(a,b){
    ....
})(window)
</code></pre>

<p>Here <code>a=window</code> but <code>b=undefined</code>, why is so?</p>
