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

If I understand this question correctly, you want something like Flow's $Shape

So, in one place, you may have something that requires the type

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

Then, in another place you want a the type with the same type as IUser just with all the fields now optional.

interface IUserOptional {
  email?: string;
  id?: number;
  phone?: string;
};

You want a way to auto-generate IUserOptional based on IUser without having to write out the types again.

Now, I don't think this is possible in Typescript. Things may change in 2.0, but I don't think we're even close to something like this in Typescript yet.

You could look at a pre-compiler which would generate such code for you before typescript runs, but that doesn't sound like a trivial thing to do.

With this problem in mind, I can only suggest you try Flow instead. In flow you can just do $Shape to generate the type you want programmatically. Of course, Flow differs from Typescript in many big and small ways, so keep that in mind. Flow is not a compiler, so you won't get things like Enums and class implementing interfactes