&符号(&)在TypeScript类型定义中的含义是什么？

Question

在此类型定义文件的第60359行,有以下声明:

type ActivatedEventHandler = (ev: Windows.ApplicationModel.Activation.IActivatedEventArgs & WinRTEvent<any>) => void;

&在这种背景下,印记意味着什么？

Answer 1

Typescript 中的交集类型

• TS 中类型上下文中的 A & 表示交集类型。
• 它将两种对象类型的所有属性合并在一起并创建一个新类型

例子：

type dog = {age: number, woof: Function};
type cat = {age: number, meow: Function};

// Type weird is an intersection of cat and dog
// it needs to have all properties of them combined
type weird = dog & cat;

const weirdAnimal: weird = {age: 2, woof: () => {'woof'}, meow: () => {'meow'}}

interface extaprop {
    color: string
}

type catDog = weird & extaprop; // type now also has added color
const weirdAnimal2: catDog = {age: 2, woof: () => {'woof'}, meow: () => {'meow'}, color: 'red'}


// This is different form a union type
// The type below means either a cat OR a dog
type dogOrCat = dog | cat;

Answer 2

&在类型位置意味着类型交集.

更多

https://www.typescriptlang.org/docs/handbook/advanced-types.html#intersection-types