ISO-Date Proposal

iso-date.ts

export type TZDate = `${number}-${number}-${number}Z`;
export type TZDateTime =
  | `${number}-${number}-${number}T${number}:${number}:${number}Z`
  | `${number}-${number}-${number}T${number}:${number}:${number}.${number}Z`;

export type CalDate = `${number}-${number}-${number}`;
export type CalDateTime =
  | `${number}-${number}-${number}T${number}:${number}:${number}`
  | `${number}-${number}-${number}T${number}:${number}:${number}.${number}`;

export type ISODate = TZDate | TZDateTime | CalDate | CalDateTime;

export type JSDate = Date;

export function isISODate(d: ISODate): d is ISODate;
export function isCalDate(d: ISODate): d is CalDate;
export function isTZDate(d: ISODate): d is TZDate;
export function toISODate(date: Date, mode: DateMode): ISODate;

export function isJSDate(d: ISODate | JSDate): d is JSDate;
export function toJSDate(d: ISODate, mode: DateMode): JSDate;

export type DateMode = "calendar" | "utc" | "local";

export function useDate(
  d: ISODate,
  mode: DateMode,
  fn: Fn<JSDate, string>
): string;
export function useDate(
  d: ISODate,
  mode: DateMode,
  fn: Fn<JSDate, JSDate>
): ISODate;