UpdatePanel PostBack返回后执行Javascript实例

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UpdatePanel PostBack时执行Javascript范例
之前写过一篇介绍在UpdatePanel动态更新时触发Javascript的方法，不过有网友反应不清楚实作的细节，索性就写一个极简单的程式，实际示范一下。

<%@ Page Language="C#" AutoEventWireup="true" %>

<html>

<head><title>UpdatePanel Call Javascript</title></head>

<body>

    <form id="form1" runat="server">

        <asp:UpdatePanel ID="UpdatePanel1" runat="server">

            <ContentTemplate>

                <asp:ScriptManager ID="ScriptManager1" runat="server">

                </asp:ScriptManager>

                <asp:Button ID="Button1" runat="server" Text="Button"

                onclick="Button1_Click" />

                <asp:HiddenField ID="hdnScript" runat="server" />

            </ContentTemplate>

        </asp:UpdatePanel>

        <script type="text/javascript">

        Sys.WebForms.PageRequestManager.getInstance().add_endRequest(blah);

        function blah() {

            eval($get("hdnScript").value);

        </script>

    </form>

<script type="text/C#" runat="server">

protected void Button1_Click(object sender, EventArgs e)

    hdnScript.Value = "alert('I did it!');";

</script>

</body>

</html>运作的原理是利用add_endRequest()在每次UpdatePanel Postback时触发blah()函数，blah()会用eval()执行Hidden栏位的字串值，所以在Server-Side将要执行的Javascript Code以字串方式传回，按下按钮后就会被执行。 That's all, folks.

PS: 顺便宣导一下资安观念，传回的Javascript Code不宜开放给User自行输入或更动，不然会造成XSS攻击的漏洞。
PS2: 用VS 2008写这段Code时，输入Sys.WebForms.PageRequestManager.getInstance()后还会提示add_Request，不亦快哉!!

Javascript牛人Ammon再露了一手，提供更简便的做法ScriptManager.RegisterStartupScript()，在此谢过:

<%@ Page Language="C#" AutoEventWireup="true" %>

<html>

<head><title>UpdatePanel Call Javascript</title></head>

<body>

    <form id="form1" runat="server">

        <asp:ScriptManager ID="ScriptManager1" runat="server">

        </asp:ScriptManager>

        <asp:UpdatePanel ID="UpdatePanel1" runat="server">

            <ContentTemplate>

                <asp:Button ID="Button1" runat="server" Text="Button"

                onclick="Button1_Click" />

            </ContentTemplate>

        </asp:UpdatePanel>

    </form>

<script type="text/C#" runat="server">

protected void Button1_Click(object sender, EventArgs e)

    ScriptManager.RegisterStartupScript(Button1, typeof(Button),

        "alert", "alert('Amazing');", true);

</script>

</body>

</html>