am using the following code to add text box values if any of the textbox is not given value it is showing NaN in total textbox how to avoid it

 <script>
     function totalValue()
     {
          var a = document.getElementById("a").value;
          var b = document.getElementById("b").value;
          var c = document.getElementById("c").value;   
          var d = parseFloat(a)+ parseFloat(b)+ parseFloat(c);
          document.getElementById("total").value = d;
     }

 </script>

am using the following code to add text box values if any of the textbox is not given value it is showing NaN in total textbox how to avoid it

 <script>
     function totalValue()
     {
          var a = document.getElementById("a").value;
          var b = document.getElementById("b").value;
          var c = document.getElementById("c").value;   
          var d = parseFloat(a)+ parseFloat(b)+ parseFloat(c);
          document.getElementById("total").value = d;
     }

 </script>

• javascript
• html

• what do you mean? if value of a is not given, d has the sum of only b and c? – Lonely Commented Jul 31, 2013 at 7:20
• 3 parseFloat('0' + a) – meze Commented Jul 31, 2013 at 7:20
• but it is not adding those two and giving output as NaN – user2419839 Commented Jul 31, 2013 at 7:21

3 Answers 3

Try this:

 <script>
     function totalValue()
     {
          var a = document.getElementById("a").value || 0;
          var b = document.getElementById("b").value || 0;
          var c = document.getElementById("c").value || 0;   
          var d = parseFloat(a)+ parseFloat(b)+ parseFloat(c);
          document.getElementById("total").value = d;
     }

 </script>

Fiddle: http://jsfiddle/AvzwM/

You can append a 0 to a string:

 <script>
     function totalValue()
     {
          var a = document.getElementById("a").value;
          var b = document.getElementById("b").value;
          var c = document.getElementById("c").value;   
          var d = parseFloat('0' + a)+ parseFloat('0' + b)+ parseFloat('0' + c);
          document.getElementById("total").value = d;
     }

 </script>

<script>
//checks if given text in text box is a number or unwanted string
filterInt = function (value)
{
if(/^\-?[0-9]+$/.test(value))
return Number(value);
return NaN;
}

 function totalValue()
 {
      var a = document.getElementById("a").value;
      var b = document.getElementById("b").value;
      var c = document.getElementById("c").value;   
      a=filterInt(a)||0; //if it is a string, convert it to a Nan and then if NaN,                  convert to zero
      b=filterInt(b)||0;
      c=filterInt(c)||0;
      var d = parseFloat(a)+ parseFloat(b)+ parseFloat(c);
      document.getElementById("total").value = d;
 }