<script runat="server">
</script>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
<script type="text/javascript">
function getClientId()
{
var paraId1 = '<%= Button1.ClientID %>';//注册控件1
var paraId2 = '<%= TextBox1.ClientID %>';//注册控件2
return {Id1:paraId1,Id2:paraId2};//生成访问器
}
</script>
<script type="text/javascript" src="JScript.js"></script>//引用外部js
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" />
<input id="Button2" type="button" value="button" onclick="ChangeText();" />
</asp:Content>
JScript.js
function ChangeText()
{
var btn=document.getElementById(getClientId().Id1);
btn.value="from extended js";
var btn=document.getElementById(getClientId().Id2);
btn.value="from extended js";
}
方案二：使用JS全局变量
还有一种方法也比较OO，就是使用JS全局变量，同样，也需要在Default5.aspx中添加一段JS代码，作为全局变量，来提供ClientID：
<script type="text/javascript">
var globals = {};
globals.controlIdentities = {};
globals.controlIdentities.someControl1 = '<%= Button1.ClientID %>';
globals.controlIdentities.someControl2 = '<%= TextBox1.ClientID %>';
</script>
<script type="text/javascript" src="JScript.js"></script>
接下来，我们在JScript.js中，就可以这样来实现需求：
function ChangeText()
{
var btn=document.getElementById(globals.controlIdentities.someControl1);
btn.value="from extended js";
}
globals.controlIdentities.someControl1，同样，也支持VS2008很蹩脚的JS智能提示，打上“.”之后就可以在提示中选择someControl1了
下面是一个完整的Demo代码：
Default5.aspx
<%@ Page Language="C#" MasterPageFile="~/MasterPage.master" Title="Untitled Page" %>
<script runat="server">
</script>
<asp:Content ID="Content1" ContentPlaceHolderID="head" Runat="Server">
<script type="text/javascript">
var globals = {};
globals.controlIdentities = {};
globals.controlIdentities.someControl1 = '<%= Button1.ClientID %>';
globals.controlIdentities.someControl2 = '<%= TextBox1.ClientID %>';
</script>
<script type="text/javascript" src="JScript.js"></script>
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="ContentPlaceHolder1" Runat="Server">
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:Button ID="Button1" runat="server" Text="Button" />
<input id="Button2" type="button" value="button" onclick="ChangeText();" />
