type UserId = number;
type PostId = number;

const userId: UserId = 888;
const postId: PostId = 24;
const register = (userId: UserId, postId: PostId) => {...}

register(postId, userId) // 引数の順番をミスっているが、NoError!!
type UserId = number & { "UserId": never };
type PostId = number & { "PostId": never };
type Branded<Type, Data extends string> = Type & { [key in Data]: never };
type UserId = Branded<number, "UserId">;
const makeUserId = (n: number) => n as UserId;
// 型の定義
type Branded<Type, Data extends string> = Type & { [key in Data]: never };
type UserId = Branded<number, "UserId">;
type PostId = Branded<number, "PostId">;

// id生成用関数を定義
export const makeUserId = (n: number) => n as UserId;
export const makePostId = (n: number) => n as PostId;

// idを生成
const userId = makeUserId(888);
const postId = makePostId(24);

const register = (userId: UserId, postId: PostId) => {};
register(postId, userId); // error!
// idを生成
const userId = makeUserId(888);
const postId = 24;	// makePostIdをしていない

register(userId, postId); // error!
const userId = makeUserId(888) as PostId; // error!
const userId = makeUserId(888);
const a = userId + userId	// number
type Id<T extends string> = number;
type UserId = Id<"UserId">;
type PostId = Id<"PostId">;

const userId = 24 as UserId; // number。この時点でムリってる
const postId = 24 as PostId; // number

const register = (userId: UserId, postId: PostId) => {};
register(userId, postId); // 引数の順番をミスっているが、NoError!!