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Mastering TypeScript

Abstract Class Methods

Explore how to use abstract class methods in TypeScript to enforce implementation requirements in derived classes. Understand managing inherited method calls with the super keyword and applying this pattern to real-world class hierarchies.

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Abstract class methods in TypeScript

An abstract class method is similar to an abstract class in that it is designed to be overridden. In other words, declaring a class method as abstract means that a derived class must provide an implementation of this method. For this reason, abstract class methods are not allowed to provide a function implementation.

As an example of this, let’s update the EmployeeBase class:

TypeScript 4.9.5
// Define an abstract class EmployeeBase with the following properties and methods:
// - `id` property of type number
// - `name` property of type string
// - `doWork` method with no return type (abstract method)
// - constructor that initializes `id` and `name` properties with `id` and `name` arguments
abstract class EmployeeBase {
  public id: number;
  public name: string;
  // Abstract method with no implementation, to be overridden by derived classes
  abstract doWork(): void;
  constructor(id: number, name: string) {
    this.id = id;
    this.name = name;
  }
}
Abstract class defining methods and properties

Here, we have added a class method named ...