Prevent modal popup to open on PostBack using JavaScript in ASP.Net

Hi nedash,

Use below code.

HTML

<asp:ImageButton ID="Image1" runat="server" ImageUrl="~/find.png"></asp:ImageButton>
<div id="openModal7" class="modalDialog">
    <div>
        <div class="deleteMes4">
            <asp:Image ID="Image2" runat="server" ImageUrl="https://cdnjs.cloudflare.com/ajax/libs/galleriffic/2.0.1/css/loader.gif" CssClass="imgsaveM lbldelmes"></asp:Image>
        </div>
    </div>
</div>
<script type="text/javascript" src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script type="text/javascript">
    $(function () {
        var chkPostBack = '<%= Page.IsPostBack.ToString().ToLower() %>';
        if (chkPostBack == 'false') {
            ShowModal();
            setTimeout(function () {
                HideModal();
            }, 3000);
        } else {
            HideModal();
        }
    });
    function ShowModal() {
        document.getElementById("openModal7").style.display = "block";
    }

    function HideModal() {
        document.getElementById("openModal7").style.display = "none";
    }
</script>