What's going on with this rather peculiar JavaScript syntax
<p>The following JavaScript code:</p>

<pre><code>alert(2 .x);
</code></pre>

<p>Alerts 'undefined' (See it here: <a href="http://jsfiddle.net/Rp4wk/" rel="nofollow">http://jsfiddle.net/Rp4wk/</a>) </p>

<p>(Note: The space between the '2' and '.x' is intended)</p>

<p>Simple question: Why? Especially when the following yield syntax errors:</p>

<pre><code>alert(2.x);
alert(2. x);
</code></pre>

<p>Anyone?</p>
