使用 Typescript 的 Pick 检索特定类型的所有键

Question

Is there a way to use Pick<T, K> to extract all keys of a certain type?

Example:

type MyObject = {
  a: string;
  b: number;
  c: string;
  d: boolean;
}

I want to extract all string types, so final type will be:

type NewType = {
  a: string;
  c: string;
}

Answer 1

First you'll need to extract all keys which have string value types:

type StringKeys<T> = { [P in keyof T]: T[P] extends string ? P : never }[keyof T]

type NewType = Pick<MyObject, StringKeys<MyObject>>; // { a: string; c: string; }

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