有没有办法将 Map<K,V> 类型转换为 Object 类型？

Question

比方说，我有这个：

const keys = ["name","age"] as const;

type values = [string, number];

const obj : Object<keys,values> = {

    name : "foo", age : 20

} // as Map<keys,values> valid !

const obj2 : Object<keys,values> = {

    name : "foo"

} // as Map<keys,values> error, age is missing!

const obj3 : Object<keys,values> = {

    name : "foo", age : null

} // as Map<keys,values> error, age is not a number!

我想从键和值数组创建一个对象类型。我该怎么做 ？

Answer 1

type keys = ['name', 'age']

type values = [string, number]

type ZipTuple<T extends readonly any[], U extends readonly any[]> = {

  [K in keyof T]: [T[K], K extends keyof U ? U[K] : never]

}

type KeyValTuplesToObject<K extends readonly PropertyKey[], V extends readonly any[]> = ZipTuple<

  K,

  V

>[number] extends infer Z

  ? [Z] extends [[any, any]]

    ? { [P in Z[0]]: Extract<Z, [P, any]>[1] }

    : never

  : never

type Obj = KeyValTuplesToObject<keys, values>

const obj: Obj = {

  name: 'foo',

  age: 20

} // as Map<keys,values> valid !

const obj2: Obj = {

  name: 'foo'

} // as Map<keys,values> error, age is missing!

const obj3: Obj = {

  name: 'foo',

  age: null

} // as Map<keys,values> error, age is not a number!

Answer 2

你在这里有两个问题：

1. Objecttype 不是你想要的。Object在 TS 中代表任何非原始类型，并且它不是通用的。

2. 普通 JS 对象与对象属于不同的类型Map，尽管它们都继承自 Object 原型。

解决方案：

// Define correct type for your object

type MyObject = {

  'name': string;

  'age': number;

}

const obj: MyObject  = {

  name: "foo",

  age: 20

}

// Create Map from object

const map = new Map(Object.entries(obj));

现在map自动推断为Map<string, string | number>