Learn React with TypeScript 3

Extending classes

Classes can extend other classes. This is the same concept as interfaces extending other interfaces, which we covered in the Extending interfaces section. This is a way for class properties and methods to be shared with child classes.

As with interfaces, we use the extends keyword followed by the class we are extending. Let's look at an example:

1. Let's create a ProductWithDiscountCodes from our Product class:

class Product {  name: string;  unitPrice: number;}interface DiscountCode {  code: string;  percentage: number;}class ProductWithDiscountCodes extends Product {  discountCodes: DiscountCode[];}

2. We can then consume the ProductWithDiscountCodes class as follows, leveraging properties from the base class as well as the child ...