Diff
题目
Github: Diff
获取两个接口类型中的差值属性。
interface Foo {
a: string
b: number
}
interface Bar {
a: string
c: boolean
}
type Result1 = Diff<Foo, Bar> // { b: number, c: boolean }
type Result2 = Diff<Bar, Foo> // { b: number, c: boolean }解题思路
此解题思路来自 type-challenges#3014
在对象中使用 | 与 & ，与在非对象中使用存在语义上的差异。
在集合对象中使用联合类型 | ， 官网 working-with-union-types 有如下说明:
Notice that given two sets with corresponding facts about each set, only the intersection of those facts applies to the union of the sets themselves.
interface Foo {
name: string
age: string
}
interface Bar {
name: string
age: string
gender: number
}
type result = keyof (Foo | Bar) // "name" | "age"在集合对象中使用交集类型 & ，可以见 intersection-types 给出的 demo:
interface Colorful {
color: string
}
interface Circle {
radius: number
}
type ColorfulCircle = keyof (Colorful & Circle) // "color" | "radius"结合 & 与 | 的使用，我们能立马写出比如类型 diff
答案
type Diff<O, O1> = Omit<O & O1, keyof (O | O1)>验证
interface Foo {
name: string
age: string
}
interface Bar {
name: string
age: string
gender: number
}
interface Coo {
name: string
gender: number
}
type cases = [
Expect<Equal<Diff<Foo, Bar>, { gender: number }>>,
Expect<Equal<Diff<Bar, Foo>, { gender: number }>>,
Expect<Equal<Diff<Foo, Coo>, { age: string, gender: number }>>,
Expect<Equal<Diff<Coo, Foo>, { age: string, gender: number }>>,
]