constructor() {
 this.now = new Date();
 this.nowYear = this.now.getYear(); //當前年 
 this.nowMonth = this.now.getMonth(); //當前月 
 this.nowDay = this.now.getDate(); //當前日 
 this.nowDayOfWeek = this.now.getDay(); //今天是本周的第幾天 
 this.nowYear += (this.nowYear < 2000) ? 1900 : 0;
}
//格式化數字
formatNumber(n) {
 n = n.toString()
 return n[1] ? n : '0' + n
}
//格式化日期
formatDate(date) {
 let myyear = date.getFullYear();
 let mymonth = date.getMonth() + 1;
 let myweekday = date.getDate();
 return [myyear, mymonth, myweekday].map(this.formatNumber).join('-');
}
//獲取某月的天數
getMonthDays(myMonth) {
 let monthStartDate = new Date(this.nowYear, myMonth, 1);
 let monthEndDate = new Date(this.nowYear, myMonth + 1, 1);
 let days = (monthEndDate - monthStartDate) / (1000 * 60 * 60 * 24);
 return days;
}
//獲取本季度的開始月份
getQuarterStartMonth() {
 let startMonth = 0;
 if (this.nowMonth < 3) {
  startMonth = 0;
 }
 if (2 < this.nowMonth && this.nowMonth < 6) {
  startMonth = 3;
 }
 if (5 < this.nowMonth && this.nowMonth < 9) {
  startMonth = 6;
 }
 if (this.nowMonth > 8) {
  startMonth = 9;
 }
 return startMonth;
}

//獲取今天的日期
 getNowDate() {
 return this.formatDate(new Date(this.nowYear, this.nowMonth, this.nowDay));
 }
 //獲取本周的開始日期
 getWeekStartDate() {
 return this.formatDate(new Date(this.nowYear, this.nowMonth, this.nowDay - this.nowDayOfWeek + 1));
 }
 //獲取本周的結束日期
 getWeekEndDate() {
 return this.formatDate(new Date(this.nowYear, this.nowMonth, this.nowDay + (6 - this.nowDayOfWeek + 1)));
 }
 //獲取本月的開始日期
 getMonthStartDate() {
 return this.formatDate(new Date(this.nowYear, this.nowMonth, 1));
 }
 //獲取本月的結束日期
 getMonthEndDate() {
 return this.formatDate(new Date(this.nowYear, this.nowMonth, this.getMonthDays(this.nowMonth)));
 }
 //獲取本季度的開始日期
 getQuarterStartDate() {
 return this.formatDate(new Date(this.nowYear, this.getQuarterStartMonth(), 1));
 }
 //獲取本季度的結束日期 
 getQuarterEndDate() {
 return this.formatDate(new Date(this.nowYear, this.getQuarterStartMonth() + 2, this.getMonthDays(this.getQuarterStartMonth() + 2)));
 }
 //獲取本年的開始日期
 getYearStartDate() {
 return this.formatDate(new Date(this.nowYear, 0, 1));
 }
 //獲取本年的結束日期
 getYearEndDate() {
 return this.formatDate(new Date(this.nowYear, 11, 31));
 }

const GetPeriod = require("../../utils/getperiod.js");

this.time = new GetPeriod();

//獲取本年的結束日期
let end = this.time.getYearEndDate();

git clone git@github.com:Rattenking/GetPeriod.git