我如何转换 TypeScript 类型？

Question

I have the code

interface IProps {
  name: string;
  age: number;
}

I want to get

type Result = {
  key: 'name',
  value: string
} | {
  key: 'age',
  value: number
}

Is there any good way?

Answer 1

COnsider this example:

interface IProps {
    name: string;
    age: number;
}

type Distribute<Obj, Keys extends keyof Obj> = Keys extends any ? { key: Keys, value: Obj[Keys] } : never

type Builder<T> = Distribute<T, keyof T>

// type Result = {
//     key: "name";
//     value: string;
// } | {
//     key: "age";
//     value: number;
// }
type Result = Builder<IProps>

Playground

Here you can find more information about distributivity

This line of code { key: Keys, value: Obj[Keys] } is applied to each IProps key separately because of distributivity

PS There is also an alternative way:

type AlternativeWay<T> = {
    [Prop in keyof T]: {
        key: Prop,
        value: T[Prop]
    }
}[keyof T]


type Result = AlternativeWay<IProps>