TypeScript：将联合类型映射到另一个联合类型

Question

是否可以在 TypeScript 中将一个联合类型映射到另一个联合类型？

我希望能够做什么

例如给定联合类型 A:

type A = 'one' | 'two' | 'three';

我希望能够将其映射到联合类型 B：

type B = { type: 'one' } | { type: 'two'} | { type: 'three' };

我试过的

type B = { type: A };

但这会导致：

type B = { type: 'one' | 'two' | 'three' };

这不是我想要的。

Answer 1

You can use conditional type for distributing over the members of the union type (conditional type always takes only one branch and is used only for its distributive 属性, 我这个方法是从)

学来的

type A = 'one' | 'two' | 'three';

type Distribute<U> = U extends any ? {type: U} : never;

type B = Distribute<A>;

/*
type B = {
    type: "one";
} | {
    type: "two";
} | {
    type: "three";
}
*/

TypeScript：将联合类型映射到另一个联合类型

TypeScript: Map union type to another union type

discriminated-union

typescript