Push Down Method

Goal

Methods used by only one subclass live with that subclass, not on the shared superclass.

Before the refactoring

class Employee {
  quota() { /* used only by Salesperson */ }
}

After the refactoring

class Salesperson extends Employee {
  quota() { /* ... */ }
}

Savings

The superclass surface shrinks; subclasses that don't need the method aren't burdened by it.

Note

If the method is occasionally needed in the parent, pushing it down forces awkward type checks back at consumers — verify usage first.