title: jquery calculation - NaN and formatting
body: <p>This is my code: </p>
  
  <pre><code>&lt;script src="js/jquery.js" type="text/javascript"&gt;&lt;/script&gt;
  &lt;script src="js/jquery.field.js" type="text/javascript"&gt;&lt;/script&gt;
  &lt;script src="js/jquery.calculation.js" type="text/javascript"&gt;&lt;/script&gt;
  &lt;script&gt;
  
  $(function() {
        $('input[name^=sum]').keyup(function() {
              var sum1 = parseFloat($('input[name=sum1]').val());
              var sum2 = parseFloat($('input[name=sum2]').val()); 
      var sum3 = parseFloat($('input[name=sum3]').val()); 
  
  
              $('#c_card_amount').val(sum1*sum3/100);
      $('#total_inc_charges').val((sum1*sum3/100)+sum1);
      });
  });
  
  &lt;/script&gt;
  </code></pre>
  
  <p>My questions:</p>
  
  <ol>
  <li><p>If no value is in <code>sum1</code> the <code>c_card_amount</code> and the <code>total_inc_charges</code> are <code>NaN</code>. How can I put a condition in this that says if no value is in <code>sum1</code> just show 0 in <code>total_inc_charges</code>. I've read about this but I could not figure out the answer in terms of my code. </p></li>
  <li><p>My second question is: how can I show the numbers in 1,000.00 format for instance? </p></li>
  </ol>