Nodejs Day of Year getDayOfYear()

Method Source Code

Date.prototype.getDayOfYear = function() {
  var dayMs = 24 * 60 * 60 * 1000;
  var janFirst = new Date(this.getFullYear(),0,1);
  // 'date' is date at 2 am to ensure that daylight saving doesn't
  // screw up the calculation of ms since year start.
  var date = new Date(this.getFullYear(), this.getMonth(), this.getDate(), 2)
  return Math.ceil((date-janFirst) / dayMs);
};

Related

1. getDOY()

   Date.prototype.getDOY = function() {
       var dayCount = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
       var mn = this.getMonth();
       var dn = this.getDate();
       var dayOfYear = dayCount[mn] + dn;
       if (mn > 1 && this.isLeapYear()) dayOfYear++;
       return dayOfYear;
   };
   

2. getDOY()

   ---
   ---
   Date.prototype.getDOY = function() {
     var onejan = new Date(this.getFullYear(),0,1);
     return Math.ceil((this - onejan) / 86400000);
   

3. getDOY()

   Date.prototype.getDOY = function () {
       var onejan = new Date(this.getFullYear(), 0, 1);
       return Math.ceil((this - onejan) / 86400000) + 1;
   };
   

4. getDayOfYear()

   Date.prototype.getDayOfYear = function() {
     const janFirst = new Date(this.getFullYear(), 0, 0);
     const diff = this - janFirst;
     const millisPerDay = 86400000;
     return Math.floor(diff / millisPerDay);
   };
   

5. getDayOfYear()

   Date.prototype.getDayOfYear = function () {
       var num = 0;
       Date.daysInMonth[1] = this.isLeapYear() ? 29 : 28;
       for (var i = 0; i < this.getMonth(); ++i) {
           num += Date.daysInMonth[i];
       return num + this.getDate() - 1;