react-day-picker/src/formatters/formatDay.ts

Customizable Date Picker for React

import { DateLib, type DateLibOptions } from "../classes/DateLib.js";

/**
 * Formats the day date shown in the day cell.
 *
 * @defaultValue `d` (e.g., "1").
 * @param date The date to format.
 * @param options Configuration options for the date library.
 * @param dateLib The date library to use for formatting. If not provided, a new
 *   instance is created.
 * @returns The formatted day as a string.
 * @group Formatters
 * @see https://daypicker.dev/docs/translation#custom-formatters
 */
export function formatDay(
  date: Date,
  options?: DateLibOptions,
  dateLib?: DateLib
) {
  return (dateLib ?? new DateLib(options)).format(date, "d");
}