Nested Object types

Creating nested object types

To understand how nested object types work, let's move back to the snippet of code where the type Person was created:

type Person = {
  name: string;
  age: number;
  isAdult: boolean;
};

On that type, let's implement one more property which is related to a person, their address. Well, normally a person address would not be represented by one of the basic types we have mentioned before. This is most of the times, represented by another object, with properties such as: street, zipcode, number, city, among others.

This is then a good opporunity to make use of nested types to implement this address property for Person. This can be done in two different ways:

1. Creating it directly inside the Person type, like displayed below:

   type Person = {
     name: string;
     age: number;
     isAdult: boolean;
     address: {
       street: string;
       city: string;
       country: string;
     };
   };

2. Creating the custom type Address and making use of this right inside the Person type

   This approach is commonly used in situations where a type definition may be necessary into other parts of your code, as well as to provide some extra flexiblity.

   type Address = {
     street: string;
     city: string;
     country: string;
   };
   
   type Person = {
     name: string;
     age: number;
     isAdult: boolean;
     address: Address;
   };
   
   type Company = {
     owner: string;
     address: Address;
   };