Add two numbers in asp.net page using Javascript
<p>Given Two text Boxes. (TextBox1 &amp; TextBox2), I want add two numbers (using the two text boxes) and show the result in the thrid textbox (TextBox3) <em>instantly</em> i.e without pressing a asp.net button. This is to be done using Javascript. I'm new to javascript so dont have much idea.</p>

<p>This is the asp.net page.</p>

<pre><code>&lt;%@ Page Language="C#" AutoEventWireup="true"  CodeFile="Default.aspx.cs" Inherits="_Default" %&gt;

&lt;!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"&gt;

&lt;html xmlns="http://www.w3.org/1999/xhtml"&gt;
&lt;head runat="server"&gt;
    &lt;title&gt;Untitled Page&lt;/title&gt;
&lt;/head&gt;
&lt;body&gt;
    &lt;form id="form1" runat="server"&gt;
    &lt;div&gt;

        Box1
        &lt;br /&gt;
        &lt;asp:TextBox ID="TextBox1" runat="server"&gt;&lt;/asp:TextBox&gt;
        &lt;br /&gt;
        &lt;br /&gt;
        Box2&lt;br /&gt;
        &lt;asp:TextBox ID="TextBox2" runat="server"&gt;&lt;/asp:TextBox&gt;
        &lt;br /&gt;
        &lt;br /&gt;
        Box3&lt;br /&gt;
        &lt;asp:TextBox ID="TextBox3" runat="server"&gt;&lt;/asp:TextBox&gt;

    &lt;/div&gt;
    &lt;/form&gt;
&lt;/body&gt;
&lt;/html&gt;
</code></pre>
