Uncaught TypeError: Cannot read property 'data' of null using array
<p>My JS is throwing this error even when i'm checking if it's null or not. Maybe one of you guys could help me with this one.</p>

<pre><code>if (typeof(this.callbacks['changed']) !== 'undefined') {
        if (typeof(obj['item']['data']) !== 'undefined' &amp;&amp; 
           (typeof(obj['item']['data'] != null))) {
            this.callbacks['changed'](row, obj['item']['data']);
        }
    }
</code></pre>

<p>This error: </p>

<blockquote>
  <p>Uncaught TypeError: Cannot read property 'data' of null </p>
</blockquote>

<p>already starts here: <code>&amp;&amp; (typeof(obj['item']['data'] != null)</code></p>