CODEWITHSUNDEEP
javascriptreactjstypescripttypes
Red Baron
Red Baron

Reputation: 7672

How to replace types in typescript?

say I have

type Person = {
  name: string
  hobbies: Array<string>
}

and then this: const people: Array<Person> = [{name: "rich", age: 28}]

how do I add age AND replace hobbies with say a different type (Array<number>) to keep it simple

I know I can use omit to get rid of a property or intersections to add a property but I'm struggling to work it out

Obviously this is wrong but I want something like that

type Hobbies = Array<number>
type NewPerson = Omit<Person, "hobbies"> & Hobbies & Age

const people: Array<NewPerson> = [{name: "rich", age: 28, hobbies: [1,2,3]}]

Upvotes: 1

Views: 65

Answers (3)

T.J. Crowder
T.J. Crowder

Reputation: 1075049

You're right you'd use Omit and an intersection. To remove hobbies and add age you'd do Omit and intersect with an object type defining age and the new version of hobbies:

type Person = {
    name: string;
    hobbies: Array<string>;
};

type NewPerson = Omit<Person, "hobbies"> & { age: number, hobbies: number[] };

const people: Array<NewPerson> = [{ name: "rich", age: 28, hobbies: [1,2,3] }];

Playground link

Upvotes: 2

delia
delia

Reputation: 136

Maybe the example below helps.

type NewPerson = Omit<Person, "hobbies"> & { hobbies: Array<number>, age: number }

const people: Array<NewPerson> = [{name: "rich", age: 28, hobbies: [1, 2, 3]}]

Use the Omit type to remove the hobbies property from the Person type and then add in the new hobbies and age properties.

Upvotes: 2

Titian Cernicova-Dragomir
Titian Cernicova-Dragomir

Reputation: 250056

You neet to intersect with object types that have the extra properties you want to add


type Hobbies = { numbers: Array<number>}
type NewPerson = Omit<Person, "hobbies"> & Hobbies  & { age: number }

const people: Array<NewPerson> = [{name: "rich", age: 28, numbers: [1,2,3]}]

Playground Link

Upvotes: 2

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