从数组中取出每个元素的类型

// 例如我们有一个水果数组
const fruits = ["orange", "mongo", "apple"] as const

// 如果想要取出数组中所有元素的联合类型可以利用 number 取得
type Fruit = (typeof fruits)[number] // type Fruit = "orange" | "mongo" | "apple"

// 或
type Orange = (typeof fruits)[0] // type Orange = "orange"

// 真实世界的用例
const fruitsOptions = [
  {
    label: "橘子",
    value: "orange"
  },
  {
    label: "芒果",
    value: "mongo"
  },
  {
    label: "苹果",
    value: "apple"
  },
] as const

const [fruit, setFruit] = useState<(typeof fruitsOptions)[number]["value"]>()

<Select options={fruitsOptions} value={fruit} onChange={setFruit} />