code: function(a, b){
  		
  			//Get value for "a" and "b" element
  			var aValue = expression(a);
  			var bValue = expression(b);
  		
  			//Check if one element is greater then the second one
  			if(aValue < bValue) return -1;
  			if(aValue > bValue) return 1;
  			return 0;
  		}
docs: Define sort action estracting values from objects