How to sort by merged cells in Google Sheet

Question

I have been using this script for sorting and so I know it works. Now I'm trying to use it on a new Google Sheet project. Except that the column I want to sort the entire sheet by isn't just one column but a merge, which I derived by merging columns 3 to 6. How do I modify my script to sort by the derived column? Here is my script:

function onEdit(event){
  var sheet = event.source.getActiveSheet();
  var editedCell = sheet.getActiveCell();

  var columnToSortBy = 3; // doing 3:6 doesn't work
  var tableRange = "A11:R82";

  if(editedCell.getColumn() == columnToSortBy){   
    var range = sheet.getRange(tableRange);
    range.sort( { column : columnToSortBy } );
  }
}

After some trials and error, I did the following, but it's still not working:

function onEdit(event){
  var sheet = event.source.getActiveSheet();
  var editedCell = sheet.getActiveCell();

  var columnToSortBy = [3,4,5,6];
  var tableRange = "A11:R82";

  if(columnToSortBy.includes(editedCell.getColumn()) ){   
    var range = sheet.getRange(tableRange);
    range.sort( { column : columnToSortBy[0] }, { column : columnToSortBy[1] },{ column : columnToSortBy[2] },{ column : columnToSortBy[3] } );
  }
}

Answer 1

Normally it's just:

range.sort([{column: 3}, {column: 4}, {column: 5}, {column: 6}]);

So based on this wouldn't it be column: 3[0] , column 3[1] etc ? I dont know, I'm just kibitzing. Give it a go!