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MapTypes

约 281 字小于 1 分钟

2026-02-11

题目

Implement MapTypes<T, R> which will transform types in object T to different types defined by type R which has the following structure

type StringToNumber = {
  mapFrom: string; // value of key which value is string
  mapTo: number; // will be transformed for number
}

Examples:

type StringToNumber = { mapFrom: string; mapTo: number;}
MapTypes<{iWillBeANumberOneDay: string}, StringToNumber> // gives { iWillBeANumberOneDay: number; }

Be aware that user can provide a union of types:

type StringToNumber = { mapFrom: string; mapTo: number;}
type StringToDate = { mapFrom: string; mapTo: Date;}
MapTypes<{iWillBeNumberOrDate: string}, StringToDate | StringToNumber> // gives { iWillBeNumberOrDate: number | Date; }

If the type doesn't exist in our map, leave it as it was:

type StringToNumber = { mapFrom: string; mapTo: number;}
MapTypes<{iWillBeANumberOneDay: string, iWillStayTheSame: Function}, StringToNumber> // // gives { iWillBeANumberOneDay: number, iWillStayTheSame: Function }

解题思路

待补充

答案

type MapTypes<T, R> = any

验证

import type { Equal, Expect } from '@type-challenges/utils'

type cases = [
  Expect<Equal<MapTypes<{ stringToArray: string }, { mapFrom: string, mapTo: [] }>, { stringToArray: [] }>>,
  Expect<Equal<MapTypes<{ stringToNumber: string }, { mapFrom: string, mapTo: number }>, { stringToNumber: number }>>,
  Expect<Equal<MapTypes<{ stringToNumber: string, skipParsingMe: boolean }, { mapFrom: string, mapTo: number }>, { stringToNumber: number, skipParsingMe: boolean }>>,
  Expect<Equal<MapTypes<{ date: string }, { mapFrom: string, mapTo: Date } | { mapFrom: string, mapTo: null }>, { date: null | Date }>>,
  Expect<Equal<MapTypes<{ date: string }, { mapFrom: string, mapTo: Date | null }>, { date: null | Date }>>,
  Expect<Equal<MapTypes<{ fields: Record<string, boolean> }, { mapFrom: Record<string, boolean>, mapTo: string[] }>, { fields: string[] }>>,
  Expect<Equal<MapTypes<{ name: string }, { mapFrom: boolean, mapTo: never }>, { name: string }>>,
  Expect<Equal<MapTypes<{ name: string, date: Date }, { mapFrom: string, mapTo: boolean } | { mapFrom: Date, mapTo: string }>, { name: boolean, date: string }>>,
]

参考

无