Javascript for loop efficiency
<p>Is</p>

<pre><code>for (var i=0, cols=columns.length; i&lt;cols; i++) { ... }
</code></pre>

<p>more efficient than </p>

<pre><code>for (var i=0; i&lt;columns.length; i++) { ... }
</code></pre>

<p>?</p>

<p>In the second variant, is <code>columns.length</code> calculated each time the condition <code>i&lt;columns.length</code> is checked ?</p>
