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常用的TS类型工具

article 2025/2/7 5:28:25

保留所有必需的属性

type GetRequired<T extends Record<string, any>> = {
  [K in keyof T as T[K] extends Required<T>[K] ? K : never]: T[K]
}

// 结果
type result = GetRequired<{ foo: number; bar?: string }>; // { foo: number }
type result1 = GetRequired<{ foo: undefined; bar?: undefined }>; // { foo: undefined }

保留可选属性

type GetOptional<T extends Record<string, any>> = {
  [K in keyof T as T[K] extends Required<T>[K] ? never : K]: T[K]
}

// 结果
type result = GetRequired<{ foo: number; bar?: string }>; // { bar?: string }
type result1 = GetRequired<{ foo: undefined; bar?: undefined }>; // { bar?: undefined }

获取必需属性的key

type RequiredKeys<T extends Record<string, any>> = keyof {
  [K in keyof T as T[K] extends Required<T>[K] ? K : never]: T[K]
}

// 结果
type result = RequiredKeys<{ a: number; b?: string }>; // 'a'
type result1 = RequiredKeys<{ a: undefined; b?: undefined; c: string; d: null }>; // 'a' | 'c' | 'd'

去除两端空白字符

type Space = ' ' | '\n' | '\t'
type Trim<S extends string> = S extends `${Space}${infer L}` | `${infer L}${Space}` ? Trim<L> : S;

// 结果
type result = Trim<' str'>; // ‘str’
type result = Trim<'str '>; // ‘str’
type result = Trim<'  str'>; // ‘str’
type result = Trim<'  str  '>; // ‘str’