why javascript not work on masterpage
<p>work on asp.net vs 05 C#.Master page header contain the bellow code</p>

<pre><code>&lt;script type="text/javascript" language="javascript" src="JScript.js"&gt;&lt;/script&gt;
</code></pre>

<p>from my one page i call the javascript method </p>

<pre><code> &lt;asp:TextBox ID="txtLength" runat="server" &gt;0&lt;/asp:TextBox&gt;

 &lt;asp:TextBox ID="txtHeight" runat="server" onchange="javascript:DoChange();"&gt;0&lt;/asp:TextBox&gt;
</code></pre>

<p>javascript method is below :</p>

<pre><code> {
      alert("hello world");**//get this alert but don't get the bellow alert.**
     var a=document.getElementById("txtLength");
     var b=document.getElementById("txtHeight");
      alert(a.value*b.value);
   }
</code></pre>

<p>want to show  value on message box .Actually want to calculate the Sft,How to ?</p>
