I have a legacy class that is rahter complex to maintain:

class OldClass {
  method1(arg1, arg2) {
      ... 200 lines of code ... 
  }

  method2(arg1) {
      ... 200 lines of code ... 
  }

  ...

  method20(arg1, arg2, arg3) {
      ... 200 lines of code ... 
  }    
}

methods are huge, unstructured and repetitive (developer loved copy/paste aprroach). I want to split each method into 3-5 small functions, whith one pulic method and several helpers.

What will you suggest? Several ideas come to my mind:

• Add several private helper methods to each method and join them in #region (straight-forward refactoring)

• Use Command pattern (one command class per OldClass method in a separate file).

• Create helper static class per method with one public method & several private helper methods. OldClass methods delegate implementation to appropriate static class (very similiar to commands).

• ?

Thank you in advance!