Given a typescript interface:
interface alpha {
name?: string;
age?: string;
sign?: string;
}
I would like to create another interface that is confined to have a limited set of properties from another interface
interface beta {
age?: string;
}
Is this possible?
If someone was to have:
interface beta {
foo?: string;
}
I'd like it to be invalid.
Great answer here: How to remove fields from a TypeScript interface via extension
So you make a "helper type" called e.g. Omit to omit certain properties from your interface:
type Omit<T, K extends keyof T> = Pick<T, Exclude<keyof T, K>>
Likewise, you can also modify the properties of your existing interface, which can be useful many times:
type Readonly<T> = {
readonly [P in keyof T]: T[P];
}
type Partial<T> = {
[P in keyof T]?: T[P];
}
Also, sometimes it's easier to turn it around. Extend alpha from beta.
interface alpha extends beta {
name?: string;
sign?: string;
}
interface beta {
age?: string;
}
const x: alpha = {
name: "foo" // valid
}
const y: beta = {
name: "where" // invalid
}
