在按钮单击上的文本框中显示结果(ASP.Net)

<asp:Button ID="Button1" runat="server" Text="单击显示结果" OnClick="Button1_Click" />
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

protected void Button1_Click(object sender, EventArgs e)
{
    TextBox1.Text = "这是结果";
}

<asp:Button ID="Button1" runat="server" Text="单击显示结果" OnClientClick="showResult()" />
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>

function showResult() {
    var xhttp = new XMLHttpRequest();
    xhttp.onreadystatechange = function () {
        if (this.readyState == 4 && this.status == 200) {
            document.getElementById("TextBox1").value = this.responseText;
        }
    };
    xhttp.open("GET", "GetResult.aspx", true);
    xhttp.send();
}

public partial class GetResult : System.Web.UI.Page
{
    protected void Page_Load(object sender, EventArgs e)
    {
        Response.Write("这是结果");
    }
}