打字稿操作员 [英] Typescript & operator

问题描述

我正在努力寻找 TypeScript 中 & 运算符的定义.我最近遇到了以下代码:

I'm struggling to find the definition of the & operator in TypeScript. I have recently come across the following code:

type IRecord<T> = T & TypedMap<T>;

那个运算符有什么作用，它与联合类型|有什么不同?

What does that operator do, and how is it different from the union type |?

推荐答案

这看起来像是来自 Intersection Types 语言规范的一部分.具体来说，& 似乎是一个 交集类型文字.至于它的作用:

This looks like it's from the Intersection Types portion of the Language Specification. Specifically, the & appears to be an intersection type literal. As for what it does:

交集类型表示同时具有多种类型的值.交集类型 A & 的值B 是类型 A 和类型 B 的值.交集类型是使用交集类型文字编写的(第 3.8.7 节).

Intersection types represent values that simultaneously have multiple types. A value of an intersection type A & B is a value that is both of type A and type B. Intersection types are written using intersection type literals (section 3.8.7).

规范继续提供有用的片段以更好地理解行为:

The spec goes on to offer a helpful snippet to better understand the behavior:

interface A { a: number }  
interface B { b: number }

var ab: A & B = { a: 1, b: 1 };  
var a: A = ab;  // A & B assignable to A  
var b: B = ab;  // A & B assignable to B

因为ab是A和的B类型，我们可以把它赋值给a 和/或 b.如果ab 只是B 类型，我们只能将它分配给b.

Because ab is both of type A and of type B, we can assign it to a and/or b. If ab were only of type B, we could only assign it to b.

您分享的代码可能来自GitHub上的这条评论，其中提到了Intersection类型.

The code you shared may be from this comment on GitHub, which mentions Intersection Types.

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