JavaScript check value
<pre><code>var it = doc.findItem('toy_total');
it.value = parseFloat(total_due) + parseFloat(sales_tax);
fixMoney(it);
</code></pre>

<p>I am trying to add total_due + sales_tax which i can do without any issues, but sometimes there is no sales tax and when that comes up i get an NaN. I am not sure how to check for null value can someone show how to do this? </p>
