TypeScript:可选的合并类型

Question

我有类型 a并输入 b ，但这应该适用于任何数量的类型。

type a = {
    first: number
}

type b = {
    second: string
    third: string
}

我想创建一个可以选择合并所有这些类型的类型，所以如果它有 second字段，它应该有 third field 也是，但不必同时拥有它们:
好的:

const aa = {
     first: 1,
     second: "hi",
     third: "hello"
}

const ab = {
     first: 1
}

const ac = {
     second: "hi",
     third: "hello"
}

坏的:

const bb = {
     first: 1,
     second: "hi"
}

我怎么能定义这样的类型？

Answer 1

type None<T> = {[K in keyof T]?: never}
type EitherOrBoth<T1, T2> = T1 & None<T2> | T2 & None<T1> | T1 & T2

type abcombined = EitherOrBoth<a,b>

查看更详细的示例:Can Typescript Interfaces express co-occurrence constraints for properties
Playground link