date-fns/esm/_lib/startOfUTCWeekYear/index.js

Modern JavaScript date utility library

import toInteger from '../toInteger/index.js';
import getUTCWeekYear from '../getUTCWeekYear/index.js';
import startOfUTCWeek from '../startOfUTCWeek/index.js'; // This function will be a part of public API when UTC function will be implemented.
// See issue: https://github.com/date-fns/date-fns/issues/376

export default function startOfUTCWeekYear(dirtyDate, dirtyOptions) {
  if (arguments.length < 1) {
    throw new TypeError('1 argument required, but only ' + arguments.length + ' present');
  }

  var options = dirtyOptions || {};
  var locale = options.locale;
  var localeFirstWeekContainsDate = locale && locale.options && locale.options.firstWeekContainsDate;
  var defaultFirstWeekContainsDate = localeFirstWeekContainsDate == null ? 1 : toInteger(localeFirstWeekContainsDate);
  var firstWeekContainsDate = options.firstWeekContainsDate == null ? defaultFirstWeekContainsDate : toInteger(options.firstWeekContainsDate);
  var year = getUTCWeekYear(dirtyDate, dirtyOptions);
  var firstWeek = new Date(0);
  firstWeek.setUTCFullYear(year, 0, firstWeekContainsDate);
  firstWeek.setUTCHours(0, 0, 0, 0);
  var date = startOfUTCWeek(firstWeek, dirtyOptions);
  return date;
}