Strange bug when checking for duplicate data, occurs only after reordering columns.

kAlex

So I have been working on my own editor for datatables for some time now, and I am currently trying to implement a check for data that already exists in the datatable.

The code below works fine initially, but as soon as i reorder the datatable by clicking the column-header it doesn't skip the selected row which I need it to do.

I have tried to console.log(dt.cell('.selected', 0).data() === dt.row(index).data().DT_RowId)
which prints the correct boolean value for every row, both initially and after the reordering of columns, but it still doesnt skip the selected row.

I have left out some code that is irrelevant for this questions, which is why you see unused variables.

A working example can be found here: https://plnkr.co/bF69ueTf8xZmX9yEEx7e?p=preview
(Error happens when: Reorder column -> select row and click edit -> submit without changing the input)

//Input validation for text-fields
var initValidation = function(tableObj){
  var dt = tableObj.s.dt;
  var isValid = false;
  var errorcount = 0;
  var matchcount = 0;
  var errorLabel, unique, ports, input, selected;

  //Looping through all inputs
  $('form[name="altEditor-form"] *').filter(':input').each(function( i ){
   
    //Checking for dublicate data in columns with unique attribute     
    if($(this).attr("data-unique") === "true"){
      input = $(this).val();
      selected = dt.cell('.selected', 0).data();
      //Looping through all data from the column
      $.each(dt.column(i+1).data(), function(index, value) { 
        //Skipping data from the selected row
        if(typeof dt.row({selected:true}, index).data() === "undefined" || selected !== dt.row(index).data().DT_RowId){ 
            if(input !== "" && input.toLowerCase() === value.toLowerCase()) {
              $(errorLabel).html("Error: Duplicate data is not allowed.");
              $(errorLabel).show();
              matchcount++
              return false; 
            }
        }
      });
    }
  }
});  

//When no errors in input and no matches are found
if(errorcount == 0 && matchcount == 0){
  isValid = true;
}

return isValid;
}

It really confuses me that it enters this if-statement, even though the statement returns true and that it only occurs after reordering:

 if(typeof dt.row({selected:true}, index).data() === "undefined" || selected !== dt.row(index).data().DT_RowId)