code: function fidjWeek(date) {
      var thursday = fidjDayOfSameWeek(date, 4);// Thursday of date's week is in right year to calculate Week number
      //var firstDayOfYear =  fidjFirstDayOfMonth(thursday.getFullYear(), 1);
      var fourthJanuary = new Date(thursday.getFullYear(), 0, 4, 0, 0, 0, 0);// This day is always in Week 1
      var thursdayOfWeek1 = fidjDayOfSameWeek(fourthJanuary, 4);// Thursday of Week 1
      var nbDays = Math.round((thursday.getTime() - thursdayOfWeek1.getTime()) / 86400000);
      return (1 + Math.floor(nbDays / 7));
  }
docs: Return the week number of the given date
  http://www.merlyn.demon.co.uk/weekcalc.htm#WNR
  
  Algorithm is to find nearest thursday, it's year
  is the year of the week number. Then get weeks
  between that date and the first day of that year.
  
  Note that dates in one year can be weeks of previous
  or next year, overlap is up to 3 days.
  
  e.g. 2014/12/29 is Monday in week  1 of 2015
  2012/1/1   is Sunday in week 52 of 2011
  
  @param {Date} date Any date of this week
  @returns {Number}