Cannot set property 'innerHTML' of null
<p>In google chrome Console, the error showing is</p>

<p><strong>Uncaught TypeError: Cannot set property 'innerHTML' of null</strong> </p>

<pre><code>var description=["a","b","c","d","e"];
var count=1;   
document.getElementById("productdescription").innerHTML = description[count-1];
</code></pre>

<p>I am calling this function on an onclick event to imagebutton</p>
