Reorder HTML table rows using drag-and-drop

I working well with it

<script>
    $(function () {

        $("#catalog tbody tr").draggable({
            appendTo:"body",
            helper:"clone"
        });
        $("#cart tbody").droppable({
            activeClass:"ui-state-default",
            hoverClass:"ui-state-hover",
            accept:":not(.ui-sortable-helper)",
            drop:function (event, ui) {
                $('.placeholder').remove();
                row = ui.draggable;
                $(this).append(row);
            }
        });
    });
</script>

The jQuery UI sortable plugin provides drag-and-drop reordering. A save button can extract the IDs of each item to create a comma-delimited string of those IDs, added to a hidden textbox. The textbox is returned to the server using an async postback.

This fiddle example reorders table elements, but does not save them to a database.

The sortable plugin takes one line of code to turn any list into a sortable list. If you care to use them, it also provides CSS and images to provide a visual impact to sortable list (see the example that I linked to). Developers, however, must provide code to retrieve items in their new order. I embed unique IDs of each item in the list as an HTML attribute and then retrieve those IDs via jQuery.

For example:

// ----- code executed when the document loads
$(function() {
    wireReorderList();
});

function wireReorderList() {
    $("#reorderExampleItems").sortable();
    $("#reorderExampleItems").disableSelection();
}

function saveOrderClick() {
    // ----- Retrieve the li items inside our sortable list
    var items = $("#reorderExampleItems li");

    var linkIDs = [items.size()];
    var index = 0;

    // ----- Iterate through each li, extracting the ID embedded as an attribute
    items.each(
        function(intIndex) {
            linkIDs[index] = $(this).attr("ExampleItemID");
            index++;
        });

    $get("<%=txtExampleItemsOrder.ClientID %>").value = linkIDs.join(",");
}

Apparently the question poorly describes the OP's problem, but this question is the top search result for dragging to reorder table rows, so that is what I will answer. I wasn't interested in bringing in jQuery UI for something so simple, so here is a jQuery only solution:

$(".grab").mousedown(function(e) {
  var tr = $(e.target).closest("TR"),
    si = tr.index(),
    sy = e.pageY,
    b = $(document.body),
    drag;
  if (si == 0) return;
  b.addClass("grabCursor").css("userSelect", "none");
  tr.addClass("grabbed");

  function move(e) {
    if (!drag && Math.abs(e.pageY - sy) < 10) return;
    drag = true;
    tr.siblings().each(function() {
      var s = $(this),
        i = s.index(),
        y = s.offset().top;
      if (i > 0 && e.pageY >= y && e.pageY < y + s.outerHeight()) {
        if (i < tr.index())
          tr.insertAfter(s);
        else
          tr.insertBefore(s);
        return false;
      }
    });
  }

  function up(e) {
    if (drag && si != tr.index()) {
      drag = false;
      alert("moved!");
    }
    $(document).unbind("mousemove", move).unbind("mouseup", up);
    b.removeClass("grabCursor").css("userSelect", "none");
    tr.removeClass("grabbed");
  }
  $(document).mousemove(move).mouseup(up);
});

.grab {
  cursor: grab;
}

.grabbed {
  box-shadow: 0 0 13px #000;
}

.grabCursor,
.grabCursor * {
  cursor: grabbing !important;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<table>
  <tr>
    <th></th>
    <th>Table Header</th>
  </tr>
  <tr>
    <td class="grab">&#9776;</td>
    <td>Table Cell 1</td>
  </tr>
  <tr>
    <td class="grab">&#9776;</td>
    <td>Table Cell 2</td>
  </tr>
  <tr>
    <td class="grab">&#9776;</td>
    <td>Table Cell 3</td>
  </tr>
</table>

Note si == 0 and i > 0 ignores the first row, which for me contains TH tags. Replace the alert with your "drag finished" logic.