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Editorial Team
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Asked: 2026-05-16T02:53:42+00:00

According to the info in: Which values browser collects as a postback data? the

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According to the info in:

Which values browser collects as a postback data?

the value of the HTML input button is sent in a post back. I’m testing in ASP.NET with IE and I am not finding this to be the case.

The markup for my test case is:

<%@ Page Language="VB" AutoEventWireup="false" CodeFile="Test.aspx.vb" Inherits="Test" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">

<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title>test postback</title>
    <script type="text/javascript">
    function doTest() {
        var button = document.getElementById("btnTest");
        button.value = "new-value";
        alert("button contents = " + button.value);
        return true;
    }
    </script>
</head>
<body>
    <form id="myForm" runat="server">
    <div>
        <asp:Panel ID="pnlTest" runat="server"
            DefaultButton="btnTest">
            Textbox: 
            <asp:TextBox ID="txtTest" runat="server" />
            <asp:Button ID="btnTest" runat="server" 
                Text="change" OnClientClick="doTest()" />
        </asp:Panel>
    </div>
    </form>

The code behind is:

Partial Class Test
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        txtTest.Text = btnTest.Text
    End Sub
End Class

My result is that the value of the input button is always “change” when the browser loads the page, but I was expecting it to be “new-value” after postback. The Javascript doTest() function is changing the value when the button is clicked.

Is there something more I’m supposed to do for ASP.NET or IE to get the input button value posted back? Or is the information about this functionality
wrong?

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1 Answer

  1. Editorial Team

    In a case like this I would probably use:

    <input type="button" ID="btnTest" runat="server" onclick="doTest()" value="change" />

    Note the runat=”server”.
    While asp:button probably renders similarly, if what you really want it an HTML button input, you can use that. Yes, ASP.NET will pick up the value on the server side.

    Also, do a view source and make sure the ASP.NET panel is not munging up the ID of the input. More generally, have you tested this without the asp:panel tag? I wonder if that affects anything.

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