calculate all textboxs value OnTextChanged
<p>i have many textboxes that the user should fill,
and i have in the bottom of the page a textbox sum.</p>

<p>i need a way to calculate the sum of all the textboxs values and put the result in the sum textbox.</p>

<p>and the sum should be updated after every textbox changed.</p>

<p>example :</p>

<pre><code>&lt;asp:TextBox ID="tb1" runat="server" onkeypress="CheckNumeric(event);" OnTextChanged="calculate" AutoPostBack="true" &gt;
&lt;asp:TextBox ID="tb2" runat="server" onkeypress="CheckNumeric(event);" OnTextChanged="calculate" AutoPostBack="true" &gt;
&lt;asp:TextBox ID="tb2" runat="server" onkeypress="CheckNumeric(event);" OnTextChanged="calculate" AutoPostBack="true" &gt;
&lt;asp:TextBox ID="tbSum" runat="server"&gt;
</code></pre>

<p>it doesn't matter if the solution should be in javascript</p>
