AngularJS orderby with empty field

Question

I am ordering a my data and its working all correcty except some fields are empty or have no value. When ordered these empty field come up first. For example when ordering n

Answer 1

I don't know why other answer suggest to put the null value records at the bottom, If I want to sort normally, means in ASC order all the null on top and in DESC order all the nulls go to bottom, I tried other answers here but could not helped me so change the code to convert the null to '' in my array and it works now smooth like this:

$scope.convertNullToBlank = function (array) {
  for (var i = 0; i < array.length; i++) {
     if (array[i].col1 === null)
       array[i].col1 = '';

     if (array[i].col2 === null)
        array[i].col2 = '';
  }
  return array;
}