.modal('show') not working code example

Example 1: $('#mymodal').modal('show') not working

<script type="text/javascript">
    $(document).ready(function(){
        $("#login-modal").modal("show");
    });
</script>

Example 2: modal.hide not working

function hideModal() {
  $("#myModal").removeClass("in");
  $(".modal-backdrop").remove();
  $('body').removeClass('modal-open');
  $('body').css('padding-right', '');
  $("#myModal").hide();
}