Js className not working
<p>again me I ahve been loking for solution for hours. Well this is my problem
JS: <code>document.getElementById("wrapper").className += " js";</code></p>

<p>HTML </p>

<pre><code>&lt;div id="wrapper"&gt;
.... 
&lt;/div&gt;
</code></pre>

<p>I get Error: Cannot read property className of null</p>
