TS utils

ts-util-snippets.ts

export type RequireAtLeastOne<T> = {
  [K in keyof T]-?: Required<Pick<T, K>> & Partial<Omit<T, K>>
}[keyof T]
  
/**
 * This is to make Omit works correctly with union type.
 * For example,
 * type A = {
 *   key1: 'A'
 *   key2: string
 * }
 * type B = {
 *   key1: 'B'
 *   key2: string
 * }
 * type C = A | B
 *
 * // This wouldn't work
 * type D = Omit<C, 'key2'>
 *
 * // We want to achieve something like this.
 * // Distributively omit.
 * type E = Omit<A, 'key2'> | Omit<B, 'key2'>
 *
 * // doc: https://www.typescriptlang.org/docs/handbook/2/conditional-types.html#distributive-conditional-types
 * // Note: this doesn't seem to work without the use of "any".
 */
// eslint-disable-next-line @typescript-eslint/no-explicit-any
export type DistributiveOmit<T, K extends keyof any> = T extends any
  ? Omit<T, K>
  : never
  
export type ExtractIterableType<T> = T extends Iterable<infer U> ? U : never