The code below will help, how one can use selector "class" to sum all the values in different input box in a Form.

<pre>&lt;pre&gt;&amp;lt;pre&amp;gt;&amp;amp;lt;script language="javascript"&amp;amp;gt;

    function sumupall(className, div){

        var elements = document.getElementsByClassName(className);
        var sum = 0;

        for(var i = 0; i &amp;amp;lt; elements.length; ++i){

            sum += parseInt(elements[i].value);

        }

        document.getElementById('totalsum').innerHTML = "Total : " + sum;
    }
&amp;amp;lt;/script&amp;amp;gt;
&amp;amp;lt;input type="text" name="box1"  class="textbox" value="2" /&amp;amp;gt;&amp;amp;lt;br /&amp;amp;gt;
&amp;amp;lt;input type="text" name="box2"  class="textbox" value="-3" /&amp;amp;gt;&amp;amp;lt;br /&amp;amp;gt;
&amp;amp;lt;input type="text" name="box3"  class="textbox" value="-3" /&amp;amp;gt;&amp;amp;lt;br /&amp;amp;gt;
&amp;amp;lt;input type="text" name="box4"  class="textbox" value="8" /&amp;amp;gt;&amp;amp;lt;br /&amp;amp;gt;
&amp;amp;lt;input type="submit" name="sum" id="sum" value="Total" onclick="sumupall('textbox', 'totalsum')" /&amp;amp;gt;&amp;amp;lt;br /&amp;amp;gt;

&amp;amp;lt;div id="totalsum"&amp;amp;gt;&amp;amp;lt;/div&amp;amp;gt;
&amp;lt;/pre&amp;gt;
&lt;/pre&gt;
</pre>