如何消除在javascript中添加表中的同一行

Question

我正在使用add函数生成一个表。我想删除在该表中添加的相同数据。每个表行我设置id但我想检查行数据是否已经在该表中退出时添加。 / p>

function adddata(pos=''){
  var main_loc = $("select#drop2 option:selected").attr('value');
  var sub_loc = $('#drop3 option:selected').attr('value');
  $("#del_row").val();

  $.ajax({
    url: "add_datas.php",
    type: "post",
    data: "main_loc="+main_loc+"&sub_loc="+sub_loc,
    success: function(result){
      $("#tab").show().html(result);

      var getDayArray = JSON.parse(result);
      var main_name=getDayArray[0][2];
      var sub_name=getDayArray[0][3];
      var map_label=getDayArray[0][4];

      var main_loc_id = $("select#drop2 option:selected").attr('value');
      var sub_loc_id = $('#drop3 option:selected').attr('value');
      var edit_id = "edit_"+main_loc_id+"_"+sub_loc_id;

      if(pos!="") {
        var table = document.getElementById("tab_grid");
        var row = table.insertRow(pos);
        row.id = edit_id;
        var cell1 = row.insertCell(0);
        var cell2 = row.insertCell(1);
        var cell3 = row.insertCell(2);
        var cell4 = row.insertCell(3);
        cell1.innerHTML = main_loc_id;
        cell2.innerHTML = sub_loc_id;
        cell3.innerHTML = main_name;
        cell4.innerHTML = sub_name;
      } else {
        $('<tr id = "'+edit_id+'"><td>'+main_loc_id+'</td><td>'+sub_loc_id+'</td><td>'+main_name+'</td><td>'+sub_name+'</td><td>'+map_label+'</td><td>'+first_level+'</td><td>'+second_level+'</td></tr></table>').appendTo('#tab_grid');
      }
    }
  });
}