javascript - 如何将元组并集转换为对象类型

Question

我有一个类型InputData，它是string或元组。我想将其转换为对象。

type InputType = File | string | boolean;
type InputData = string | [string, InputType]

type test = "username" | "password" | ["isAbove18", boolean] | ["photo", File];

在上面的类型中，只有string(给出了输入字段的名称)，其类型应设置为string。我有通用类型

type AddDefaultValues<Data extends InputData> = Data extends string ? [Data, string] : Data 
//AddDefaultValues<test> = ["username", string]| ["password", string] | ["isAbove18", boolean] | ["photo", File]

现在我的要求是将上面的类型映射到如下所示的对象。

{username: string, password: string, isAbove18: boolean, photo: File}

我尝试了很长时间，但什么也没弄清楚。请帮我解决这个问题...

Answer 1

您可以使用带有键重命名的对象映射:

type test = "username" | "password" | ["isAbove18", boolean] | ["photo", File];

type ObjMap = {
  [K in test as K extends [infer F, infer _] ? F : K]: K extends [infer _, infer S] ? S : string;
};

Playground link

另请参阅:

• Mapped types
• Type inference in conditional types
• Key Remapping in Mapped Types