BUG: TypeError: Cannot read property 'querySelector' of null

It seems like u are missing the class name or parent element ID.

below is the example of using querySelector.

<pre>
var parentElement = document.getElementById('deviceready');
var listeningElement = parentElement.querySelector('.listening');
console.log(listeningElement);

&lt;div id="deviceready"&gt;
   &lt;div class="listening"&gt;
   &lt;/div&gt;
&lt;/div&gt;

</pre>