Does Typescript support “subset types”?

Question

Let\'s say I have an interface:

interface IUser {
  email: string;
  id: number;
  phone: string;
};

Then I have a function that expects a

Answer 1

You can seperate it into different interfaces:

interface IUser {
    id: number;
};

interface IUserEmail extends IUser {
    email: string;
}

interface IUserPhone extends IUser {
    phone: string;
}

Have your method receive the base IUser interface and then check for the fields you need:

function doit(user: IUser) {
    if (user.email) {

    } else if (user.phone) {

    }
}