javascript - 从数组 Typescript 派生类型

Question

我有一个数组

const frequencyOptions = ['Daily', 'Weekly', 'Monthly'];

我需要将 Typescript Type 设置为另一个数组，该数组只能包含选项数组中的值，例如

let frequencyValues = ['Daily', 'Weekly'] // can be any combination of options array

标签： javascriptarraystypescripttypes

Answer 1

如果您要控制选项数组的创建，您可以：

const frequencyOptions = ['Daily', 'Weekly', 'Monthly'] as const;
type Option = typeof frequencyOptions[number]; // "Daily" | "Weekly" | "Monthly"

let frequencyValues: Option[] = ['Daily', 'Weekly'];

// Expect error
frequencyValues = ['foo'] // Type '"foo"' is not assignable to type '"Daily" | "Weekly" | "Monthly"'.

操场

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as const 防止文字类型扩大到string，然后我们查询元组项目类型。