Abstract properties and accessors
An abstract class can declare abstract properties and/or accessors.Any sub class will need to declare the abstract properties or be marked as abstract.Abstract properties cannot have an initializer.Abstract accessors cannot have bodies.
Example
abstract class Base {
abstract name: string;
abstract get value();
abstract set value(v: number);
}
class Derived extends Base {
name = "derived";
value = 1;
}