Hi IamAzhar,
Refer below sample.
HTML
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
<title></title>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
<script type="text/javascript" src="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css" />
</head>
<body>
<form id="form1" runat="server">
<div>
<button type="button" class="btn btn-info btn-lg" data-toggle="modal" data-target="#MyPopup">
Open Modal</button>
<div id="MyPopup" class="modal fade" role="dialog">
<div class="modal-dialog">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-hidden="true">
x</button>
<h3>
Detail</h3>
</div>
<div class="modal-body">
<div class="row">
<div class="col-md-12">
<div class="form-group">
<asp:FileUpload ID="idFileUpload" runat="server" />
</div>
</div>
</div>
</div>
<div class="modal-footer">
<asp:Button ID="btnSubmit" runat="server" Text="Save" CssClass="btn btn-success"
OnClick="btnSubmit_Click" />
<button class="btn btn-info" data-dismiss="modal" aria-hidden="true">
Close</button>
</div>
</div>
</div>
</div>
</form>
</body>
</html>
Code
C#
protected void btnSubmit_Click(object sender, EventArgs e)
{
ScriptManager.RegisterStartupScript(this, this.GetType(), " ", "alert('" + idFileUpload.PostedFile.FileName + "');", true);
}
VB.Net
Protected Sub btnSubmit_Click(ByVal sender As Object, ByVal e As EventArgs)
ScriptManager.RegisterStartupScript(Me, Me.GetType(), " ", "alert('" & idFileUpload.PostedFile.FileName & "');", True)
End Sub
Screenshot
