How to get to the first column value

I have a delete button at the end of each row

First column in the table is hidden (server row id) ,

How to I get to the first column value given the TR object?

    $('#example').on('click', 'a.editor_remove', function (e) {
        e.preventDefault();

        var oTableApi = $('#example').dataTable().api();
        var tr = $(this).closest('tr');
        alert(tr.first('td').text()); // return all the columns as one text.