设置控件是否是异步回发

aspx

    <form id="form1" runat="server">
        <asp:ScriptManager ID="ScriptManager1" runat="server">
        </asp:ScriptManager>
        
        <asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional">
            <ContentTemplate>
                <%= DateTime.Now %>
                <asp:Button ID="Button2" runat="server" Text="Button" />
            </ContentTemplate>
        </asp:UpdatePanel>
        
        <asp:Button ID="Button1" runat="server" Text="Button" OnClick="Button1_Click" />
    </form>

cs

    protected void Page_Load(object sender, EventArgs e)
    {
        ScriptManager.GetCurrent(this).RegisterAsyncPostBackControl(this.Button1);
        ScriptManager.GetCurrent(this).RegisterPostBackControl(this.Button2);
    }

    protected void Button1_Click(object sender, EventArgs e)
    {
        this.UpdatePanel1.Update();
    }