来自对象的字符串值的打字稿类型

Question

值为字符串数组的对象：

const STUFF = {
  abc: ["string_1", "string_2"],
  def: ["string_3", "string_4"],
  xyz: ["string_1", "string_2", "string_4"],
}

如何定义只允许这些数组中的值的类型？

type StuffStr = "string_1" | "string_2" | "string_3" | "string_4";

Answer 1

如果您const在 上使用断言STUFF，那么这就变成了索引问题typeof STUFF。

const STUFF = {
  abc: ["string_1", "string_2"],
  def: ["string_3", "string_4"],
  xyz: ["string_1", "string_2", "string_4"],
} as const;

type StuffStr = typeof STUFF[keyof typeof STUFF][number];
// type StuffStr = "string_1" | "string_2" | "string_3" | "string_4"

操场