javascript string.replace target can execute a function?
<p>I played with the code : </p>

<pre><code>&lt;script type="text/javascript"&gt;

var str="Visit Microsoft!";
document.write(str.replace("Microsoft",function (a){return a+"1111"}));

&lt;/script&gt;
</code></pre>

<p>and the answer is : </p>

<pre><code>Visit Microsoft1111!
</code></pre>

<p>How can it be working ?</p>

<p>I didnt see any documented code about it .</p>
