Hi arehman,
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/3.3.2/js/bootstrap.min.js"></script>
<link rel="stylesheet" href="http://maxcdn.bootstrapcdn.com/bootstrap/3.3.2/css/bootstrap.min.css" />
<script type="text/javascript">
function ShowPopup() {
$('#myModal').modal('show');
$('#myModal').on('shown.bs.modal', function () {
$('#txtUserName').focus();
});
}
</script>
</head>
<body>
<form id="form1" runat="server">
<asp:ScriptManager runat="server">
</asp:ScriptManager>
<asp:UpdatePanel runat="server">
<ContentTemplate>
<div>
<br />
<asp:Button Text="Show Popup" runat="server" ID="btnShowPopup" class="btn btn-info btn-lg"
OnClientClick="ShowPopup()" OnClick="btnShowPopup_Click" />
<div class="modal fade" id="myModal" tabindex="-1" role="dialog" aria-labelledby="myModalLabel">
<div class="modal-dialog" role="document">
<div class="modal-content">
<div class="modal-header">
<button type="button" class="close" data-dismiss="modal" aria-label="Close">
<span aria-hidden="true">×</span></button>
<h4 class="modal-title" id="myModalLabel">
Modal title</h4>
</div>
<div class="modal-body">
<input type="textusername" id="txtUserName" class="form-control" style="width: 300px"
name="name" value="" />
</div>
<div class="modal-footer">
<button type="button" class="btn btn-default" data-dismiss="modal">
Close</button>
<button type="button" class="btn btn-primary">
Save changes</button>
</div>
</div>
</div>
</div>
</div>
</ContentTemplate>
</asp:UpdatePanel>
</form>
</body>
</html>
Code
C#
protected void btnShowPopup_Click(object sender, EventArgs e)
{
ScriptManager.RegisterStartupScript((sender as Control), this.GetType(), "Popup", "ShowPopup();", true);
}
VB.Net
Protected Sub btnShowPopup_Click(sender As Object, e As System.EventArgs)
ScriptManager.RegisterStartupScript(CType(sender, Control), Me.GetType(), "Popup", "ShowPopup();", True)
End Sub
Screenshot
