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I would like to know how to achieve the following:
Show (hidden with code behind on page load) an ASP Button, when the FileUpload ASP control has a file selected.
<asp:FileUpload ID="FileUpload1" runat="server" onchange="showButton()"/>
                       <p><asp:Button ID="Button1" runat="server"  Text="Upload File" />&nbsp;</p>

When FileUpload1 has a file selected the onchange should fire
(Button 1 stays hidden and does not show)
<script type ="text/javascript" >
          function showButton() {
              document.getElementById('<%=Button1.ClientID%>').style.visibility = "visible";
but this does not work.
Please let me know what I am doing wrong.
(should Button1.Visible=true; be used in codebehind instead, if so , how in the aspx file do you tell it to do so?)
Posted 11-Jan-13 19:13pm
AU Jase624
Edited 11-Jan-13 19:14pm
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Solution 1

Try this
<asp:fileupload id="fileupload1" runat="server" onchange="showButton()" xmlns:asp="#unknown" />
<asp:button id="btnUpload" runat="server" text="Upload" style="display:none" xmlns:asp="#unknown" />
<script type ="text/javascript" >
        function showButton() {
            document.getElementById("<%=btnUpload.ClientID%>").style.display = "";
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Solution 2

if (FileUpload1.hasfile==true)
// Your Statement//////////////

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