text: 'use strict';
  
  var parse = require('../parse/index.js');
  var startOfISOWeek = require('../start_of_iso_week/index.js');
  var startOfISOYear = require('../start_of_iso_year/index.js');
  
  var MILLISECONDS_IN_WEEK = 604800000;
  
  /**
   * @category ISO Week Helpers
   * @summary Get the ISO week of the given date.
   *
   * @description
   * Get the ISO week of the given date.
   *
   * ISO week-numbering year: http://en.wikipedia.org/wiki/ISO_week_date
   *
   * @param {Date|String|Number} date - the given date
   * @returns {Number} the ISO week
   *
   * @example
   * // Which week of the ISO-week numbering year is 2 January 2005?
   * var result = getISOWeek(new Date(2005, 0, 2))
   * //=> 53
   */
  function getISOWeek(dirtyDate) {
    var date = parse(dirtyDate);
    var diff = startOfISOWeek(date).getTime() - startOfISOYear(date).getTime();
  
    // Round the number of days to the nearest integer
    // because the number of milliseconds in a week is not constant
    // (e.g. it's different in the week of the daylight saving time clock shift)
    return Math.round(diff / MILLISECONDS_IN_WEEK) + 1;
  }
  
  module.exports = getISOWeek;