Hi linkebte,
Please try the example below
<%@ Page Language="C#" %>
<!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>example</title>
</head>
<body>
<form id="form1" runat="server">
<table>
<tr>
<td>
Email:
</td>
<td>
<input id="text1" />
</td>
</tr>
<tr>
<td>
</td>
<td>
<CuteWebUI:Uploader ID="Uploader1" runat="server" >
</CuteWebUI:Uploader>
</td>
</tr>
</table>
</form>
</body>
</html>
<script type="text/javascript">
var uploader1=document.getElementById('<%=Uploader1.ClientID%>')
var text1=document.getElementById("text1");
uploader1.handlebrowse=function()
{
if (text1.value.indexOf("@") == -1) {
alert("Please input your email!");
return false;
}
}
</script>
Regards,
ken