可以使用数组值来创建具有相应字符串文字的键值类型吗？答案

【问题标题】：Possible to use array values to create key-value type with corresponding string literals?可以使用数组值来创建具有相应字符串文字的键值类型吗？
【发布时间】：2020-12-09 08:10:07
【问题描述】：

//###  Desired Implementation & Outcome:  ###//

function objectFromArray<T extends string[]>(...arr:T){
    return {/* do things */} as ObjectFromArray<T>
}

const foo = objectFromArray("a", "b", "c")

// foo === {a:"a", b:"b", c:"c"}

// typeof foo.a === "a"
// typeof foo.b === "b"
// typeof foo.c === "c"


//###  Attempt 1:  ###//
type ObjectFromArray<T extends any[]> = {[K in T[number]]: T[number]}
// no error, but results in unions instead of single values:
//   typeof foo.a === ("a" | "b" | "c")
//   typeof foo.b === ("a" | "b" | "c")
//   typeof foo.c === ("a" | "b" | "c")


//###  Attempt 2:  ###//
type ObjectFromArray<T extends string[]> = {[K in T[number]]: T[number][K]}
// Error: Type 'K' cannot be used to index type 'T[number]'.ts(2536)

【问题讨论】：

标签： typescript typescript-typings typescript-generics

【解决方案1】：

希望这就是你的意思：

function objectFromArray<T extends string[]>(...arr:T){
    return {/* do things */} as ObjectFromArray<T>
}

type ObjectFromKeyList<KeyList extends string> = {[K in KeyList]: K}
type ArrayToKeyList<T extends any[]> = T extends (infer P)[] ? P : never
type ObjectFromArray<T extends any[]> = ObjectFromKeyList<ArrayToKeyList<T>>

const foo = objectFromArray("a", "b", "c")

foo.a // type is 'a'

【讨论】：