nested property full

fullnested.ts

type TerminalType =
    | string
    | number
    | bigint
    | boolean
    | null
    | undefined
    | any[]
    | Map<any, any>
    | Set<any>
    | Date
    | RegExp
    | ((...args: any) => any)

/**
 * Deep nested keys of an interface with dot syntax
 *
 * @example
 * type t = RecursiveKeyOf<{a: {b: {c: string}}> // => 'a' | 'a.b' | 'a.b.c'
 */
export type RecursiveKeyOf<
 T,
 Prefix extends string = never,
> = T extends TerminalType
  ? never
  : {
      [K in keyof T & string]: [Prefix] extends [never]
        ? K | RecursiveKeyOf<T[K], K>
        : `${Prefix}.${K}` | RecursiveKeyOf<T[K], `${Prefix}.${K}`>;
    }[keyof T & string]
/**
* Get the type of a nested property with dot syntax
*
* Basically the inverse of `RecursiveKeyOf`
*
* @example
* type t = DeepPropertyType<{a: {b: {c: string}}}, 'a.b.c'> // => string
*/
export type DeepPropertyType<
 T,
 P extends RecursiveKeyOf<T>,
> = P extends `${infer Prefix}.${infer Rest}`
  ? Prefix extends keyof T
    ? Rest extends RecursiveKeyOf<T[Prefix]>
      ? DeepPropertyType<T[Prefix], Rest>
      : never
    : never
  : P extends keyof T
    ? T[P]
    : never


export interface RootObject {
  userNotFound: UserNotFound  
  cc: string
}

export interface UserNotFound {
  test: string
  new: cc
}

export interface cc {
  new2: string
  new3: string
}


const newData = (key: RecursiveKeyOf<RootObject>) => {
  return 'a'
}
newData('userNotFound') 
newData('cc')
newData('userNotFound.new') 
newData('userNotFound.new.new2')
newData('userNotFound.new.new3')