Nodejs Year Calculate weekOfYear()

Method Source Code

Date.prototype.weekOfYear = function () {
    var year = this.getFullYear();
    var d = new Date(this);
    d.setHours(0, 0, 0, 0);//  www . j  a v a2 s.c o  m
    var yearStart = new Date(year, 0, 1);
    d.setDate(d.getDate() + yearStart.getDay());
    var deltaDay = (d.getTime() - yearStart.getTime()) / 86400000 + 1;
    var weekNo = Math.ceil(deltaDay / 7);
    return [year, weekNo];
};

Related

1. increaseYear(num)

   var weekdays = exports.weekdays = ["sunday", "monday", "tuesday", "wednesday", "thursday", "friday", "saturday"];
   Date.prototype.increaseYear = function(num) {
     this.setUTCFullYear(this.getUTCFullYear() + num);
   Date.prototype.increaseMonth = function(num) {
     var str = this.getUTCFullYear()+"-"+(this.getUTCMonth()+num + 1)+"-"+
           this.getUTCDate()+"T"+this.getUTCHours()+":"+this.getUTCMinutes()+":"+
           this.getUTCSeconds()+"."+this.getUTCMilliseconds()+"Z";
     var date = new Date(str);
   ...
   

2. isThisYear()

   Date.prototype.isThisYear = function() {
       return new Date().getYear() == this.getYear();
   };
   

3. subYears(value)

   Date.prototype.subYears = function(value) {
     var month = this.getMonth();
     this.setFullYear(this.getFullYear() - value);
     if (month < this.getMonth()) {
       this.setDate(0);
     return this;
   };
   

4. toYearEnd()

   Date.prototype.toYearEnd = function () {
       var date = new Date(this);
       date.setMonth(12);
       date.setDate(0);
       return date;
   };
   

5. toYearStart()

   Date.prototype.toYearStart = function () {
       var date = new Date(this);
       date.setMonth(0);
       date.setDate(1);
       return date;
   };
   

6. yearStartDay()

   Date.prototype.yearStartDay = function(){
     return new Date(this.getFullYear(),0,1).getDay();