MVC 5 Javascript checkbox checked updating first row in table

I have this code and I want to be able to strikethrough the text in the same row. Can I use the row index (or the record id number on a data attribute) to get at the correct task description?

Here is my code:

function CompleteTask(x)
{
    var row = x.parentNode.parentNode;
    var customerid = $('#DeleteTask').data('id');
    var table = document.getElementById('tasks_table');
   var rows = table.getElementsByTagName('tr');
  var rowIdx = row.rowIndex;
   var selectedRow = rows[rowIdx];
   var Description = selectedRow.getElementsByClassName("TaskDescription");
  var values = selectedRow.cells;
   var col = selectedRow.cells[1].innerHTML;
    var checkbox = values[0].innerText;
   var tasktext = values[1].innerText; row.cells[1].className

  if ($("#checkbox").is(':checked'))
    {
       $("#TaskDescription").css('text-decoration', 'line-through'); // works but only on first line of table. Would like to use row index if possible please
    }
}

Thanks

Stew