Get Days in A Year - Date Polyfill

get-days-in-year.js

'use strict';
if (!Date.prototype.getDaysInYear) {
  Date.prototype.getDaysInYear = function getDaysInYear(year) {
    year = year ? year : this.getFullYear();
    var days = 0;
    for (var i = 1; i < 13; i++) {
      days += new Date(year, i, 0).getDate();
    }
    return days;
  };
}