@sometic/date-core

Date adapter contract for Sometic date-aware inputs and forms.

@sometic/date-core defines the DateAdapter interface and assertDateAdapter helper. Adapters must implement parse/format, validity, compare, add, startOf/endOf, and serialize/deserialize. No concrete calendar library ships here; implementations live in separate packages.

This contract exists so date inputs and future date pickers can stay portable. Apps choose native Date, Day.js, or date-fns without rewriting UI engines. @sometic/dom date input controllers accept a DateAdapter instead of importing a specific library.

Standout surface: DateAdapter, DateAdapterOptions (locale, weekStartsOn), DateUnit (day | month | year), ParseResult, and runtime assertion so malformed adapters fail early in tests.

Adapters: @sometic/date-native (default), @sometic/date-dayjs, @sometic/date-fns. Foundation context via @sometic/core in the wider stack. Docs: introduction and date primitives.

Install

pnpm add @sometic/date-core

npm install @sometic/date-core

yarn add @sometic/date-core

Install a concrete adapter package as well (for example @sometic/date-native).

Usage

Type against the contract when injecting an adapter:

import { assertDateAdapter, type DateAdapter } from "@sometic/date-core";

function formatIsoDate(adapter: DateAdapter, value: Date): string {
    assertDateAdapter(adapter);
    return adapter.serialize(value);
}

Consume adapter methods without caring which library backs them:

import type { DateAdapter } from "@sometic/date-core";

function addOneWeek(adapter: DateAdapter, value: Date): Date {
    return adapter.add(value, 7, "day");
}

function parseYmd(adapter: DateAdapter, text: string): Date | null {
    const result = adapter.deserialize(text);
    return result.valid ? result.date : null;
}

Peers / when not to use

No peers. This package is types/contracts only plus assertDateAdapter.

Do not expect parsing/formatting to work from @sometic/date-core alone; install an adapter. Prefer adapter packages over inventing a one-off DateAdapter unless you are integrating another calendar library.

Docs

• Introduction
• Date primitives
• Date packages

License

MIT