TS Utils

utils.ts

type WithAutocomplete<T, U = string> = T | (U & Record<never, never>)
  
type ArrayItemType<T> = T extends (infer U)[] ? U : never
  
type Optional<T, K extends keyof T> = Pick<Partial<T>, K> & Omit<T, K>;

type TupleToObject<
  T extends readonly any[],
  M extends Record<Exclude<keyof T, keyof any[]>, PropertyKey>,
> = { [K in Exclude<keyof T, keyof any[]> as M[K]]: T[K] }

export type NullifyOptionalFields<Obj extends object> = {
  [Key in keyof Obj]: undefined extends Obj[Key]
    ? Obj[Key] extends infer U | undefined
      ? U extends object
        ? NullifyOptionalFields<U> | null
        : U | null | undefined
      : Obj[Key]
    : Obj[Key] extends object
    ? NullifyOptionalFields<Obj[Key]>
    : Obj[Key]
}