<asp:ScriptManager ID="ScriptManager1" runat="server"></asp:ScriptManager>
<asp:UpdatePanel ID="UpdatePanel1" runat="server">
    <ContentTemplate>
        <!-- 这里的内容可以无回发更新 -->
        <asp:Label ID="lblMessage" runat="server" Text="初始文本"></asp:Label>
        <asp:Button ID="btnUpdate" runat="server" Text="更新" OnClick="btnUpdate_Click" />
    </ContentTemplate>
</asp:UpdatePanel>

protected void btnUpdate_Click(object sender, EventArgs e)
{
    lblMessage.Text = "更新后的文本 - " + DateTime.Now.ToString();
}

$.ajax({
    type: "POST",
    url: "YourPage.aspx/GetUpdatedContent",
    data: JSON.stringify({ param1: value1, param2: value2 }),
    contentType: "application/json; charset=utf-8",
    dataType: "json",
    success: function(response) {
        $("#targetElement").html(response.d);
    }
});

[System.Web.Services.WebMethod]
public static string GetUpdatedContent(string param1, string param2)
{
    // 处理逻辑
    return "更新后的内容";
}

// 安装Microsoft.AspNet.SignalR NuGet包
// 创建Hub类
public class UpdateHub : Hub
{
    public void SendUpdate(string message)
    {
        Clients.All.broadcastMessage(message);
    }
}

var hub = $.connection.updateHub;
hub.client.broadcastMessage = function (message) {
    $('#messages').append('<li>' + message + '</li>');
};
$.connection.hub.start();

public class DataController : ApiController
{
    public IHttpActionResult Get()
    {
        return Ok(new { message = "动态数据", time = DateTime.Now });
    }
}

fetch('/api/data')
    .then(response => response.json())
    .then(data => {
        document.getElementById('content').innerHTML = data.message;
    });