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

Customizable Date Picker for React

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

/**
 * Formats the name of a weekday to be displayed in the weekdays header.
 *
 * @defaultValue `cccccc` (e.g., "Mo" for Monday).
 * @param weekday The date representing the weekday.
 * @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 weekday name as a string.
 * @group Formatters
 * @see https://daypicker.dev/docs/translation#custom-formatters
 */
export function formatWeekdayName(
  weekday: Date,
  options?: DateLibOptions,
  dateLib?: DateLib
) {
  return (dateLib ?? new DateLib(options)).format(weekday, "cccccc");
}