有没有办法在打字稿中为具有唯一项的数组定义类型? [英] Is there a way to define type for array with unique items in typescript?

问题描述

类型应该检测数组是否有重复项并在打字稿中抛出错误?

The type should detect if the array has duplicate items and throw error in typescript?

type UniqueArray = [
  // How to implement this?
]

const a:UniqueArray = [1, 2, 3] // success
const b:UniqueArray = [1, 2, 2] // error

PS:我目前正在使用 JS 删除重复项，但是，好奇是否可以事先使用 typescript 类型捕获此错误?

PS: I'am currently removing duplicate items using JS, but, curious if this error can be captured using typescript type before hand?

推荐答案

是的！TypeScript 4.1(在撰写本文时处于测试阶段)有一种方法.方法如下:

Yes! There is a way with TypeScript 4.1 (in beta at the time of writing). This is how:

const data = ["11", "test", "tes", "1", "testing"] as const
const uniqueData: UniqueArray<typeof data> = data

type UniqueArray<T> =
  T extends readonly [infer X, ...infer Rest]
    ? InArray<Rest, X> extends true
      ? ['Encountered value with duplicates:', X]
      : readonly [X, ...UniqueArray<Rest>]
    : T

type InArray<T, X> =
  T extends readonly [X, ...infer _Rest]
    ? true
    : T extends readonly [X]
      ? true
      : T extends readonly [infer _, ...infer Rest]
        ? InArray<Rest, X>
        : false

如果相同的值出现多次，您将收到编译器错误.

You'll get a compiler error if the same value occurs more than once.

这是我的文章，更详细地描述了事情.

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