Installation

npm install @cosyte/dates

or pnpm add @cosyte/dates.

Requirements

• Node.js 22 or later, tested on 22, 24, and 26.
• ESM only. The package ships no CommonJS build, so load it with import. A Node.js release that can require() an ES module loads it that way too, but we test only import.
• TypeScript types are included. The package carries its own declarations; there is no separate @types package to install.

Dependencies

One runtime dependency, temporal-polyfill, because Temporal.PlainDate is the only widely available type that holds a calendar date with no time of day and no zone. Temporal is re-exported from this package, so you work with the same objects rather than installing a second copy: two Temporal implementations do not share instanceof.

import { Temporal, toTemporal } from "@cosyte/dates";

const admitted = toTemporal({ year: 1988, month: 5, day: 7 });
admitted instanceof Temporal.PlainDate; // => true

Check the install

import { precisionOf, toISO } from "@cosyte/dates";

console.log(toISO({ year: 1988, month: 5 }), precisionOf({ year: 1988, month: 5 }));
toISO({ year: 1988, month: 5 }); // => "1988-05"
precisionOf({ year: 1988, month: 5 }); // => "month"

If that prints 1988-05 month, the install is good. Head to the Quickstart.