Boilerplate type definition file for YOUR projects

app.d.ts

declare global {
  /**
   * (1) Global TypeScript-helpers
   * 
   * See built-in utility types to TypeScript
   * @see https://www.typescriptlang.org/docs/handbook/utility-types.html
   */

  /**
   * Get union type with generic and null
   * @example
   *   // Expect: "User | null"
   *   type MaybeUser = Nullable<User>;
   */  
  export type Nullable<T> = T | null

  /**
   * Get union type of object keys; alias for keyof T
   * @example
   *   // Expect: "foo | baz"
   *   type ObjectKeys = Keys<{foo: 1, baz: 2}>;
   */  
  export type Keys<T extends Record<string, unknown>> = keyof T

  /**
   * Get union type of object values
   * @example
   *   // Expect: "1 | 2"
   *   type ObjectValues = Values<{foo: 1, baz: 2}>;
   */  
  export type Values<T extends Record<string, unknown>> = T[Keys<T>]

  /**
   * Typed type alias for Record
   * @example
   *   type NumericHash = Indexed<string, number>;
   */  
  export type Indexed<K = string, T = unknown> = { [key: K]: T }

  /**
   * Create brand type
   * @example
   *   type ProductId = Brand<number, 'ProductId'>
   */  
  export type Brand<K, T> = K & { __brand: T }

  /**
   * (2) Global type alias
   */
  export type Phone = string

  export type Email = string

  export type Uuid = string

  export type DateIso = string

  export type Timestamp = number

  export type Penny = number

  export type Url = string

  export type ColorRgb = `rgb(${number}, ${number}, ${number})`
  export type ColorHex = `#${string}`

  export type Color = ColorRgb | ColorHex

  /**
   * (3) Global shared kernel
   * @see https://bespoyasov.me/blog/clean-architecture-on-frontend/#into-detail-shared-kernel
   */

  // TODO: Replace the types below with your shared kernel types

  export type ApiError = {
    statusCode: number 
    message: string
  }

  export type ApiResponse<T> = { data: T } | ApiError
}

export {}