The Data-dismiss completley removes the element. You would need to hide the alert if you are intending on showing it again.
For example;
<div class="alert alert-success" id="selectCodeNotificationArea" hidden="hidden">
<button type="button" class="close" data-hide="alert">×</button>
@TempData["selCode"]
</div>
and this JS
$(function(){
$("[data-hide]").on("click", function(){
$(this).closest("." + $(this).attr("data-hide")).hide();
});
});