js实现获取今日、本周、本月、本学期的开始结束日期

const getDateFn ={
    //1、 得到今天、昨天、明天日期
    //dates为数字类型，0代表今日,-1代表昨日，1代表明日，返回yyyy-mm-dd格式字符串，dates不传默认代表今日。
    getDate(dates) {
        var dd = new Date();
        var n = dates || 0;
        dd.setDate(dd.getDate() + n);
        var y = dd.getFullYear();
        var m = dd.getMonth() + 1;
        var d = dd.getDate();
        m = m < 10 ? "0" + m: m;
        d = d < 10 ? "0" + d: d;
        var day = y + "-" + m + "-" + d;
        return day;
    },
    //2、得到本周、上周、下周的起始、结束日期
    //type为字符串类型，有两种选择，"s"代表开始,"e"代表结束，dates为数字类型，不传或0代表本周，-1代表上
    getMonday(type, dates) {
        var now = new Date();
        var nowTime = now.getTime();
        var day = now.getDay();
        var longTime = 24 * 60 * 60 * 1000;
        var n = longTime * 7 * (dates || 0);
        if (type == "s") {
          var dd = nowTime - (day - 1) * longTime + n;
        };
        if (type == "e") {
          var dd = nowTime + (7 - day) * longTime + n;
        };
        dd = new Date(dd);
        var y = dd.getFullYear();
        var m = dd.getMonth() + 1;
        var d = dd.getDate();
        m = m < 10 ? "0" + m: m;
        d = d < 10 ? "0" + d: d;
        var day = y + "-" + m + "-" + d;
        return day;
    },
    //3、得到本月、上月、下月的起始、结束日期
    //type为字符串类型，有两种选择，"s"代表开始,"e"代表结束，months为数字类型，0代表本月，-1代表上月，1代表下月
    getMonth(type, months) {
        var d = new Date();
        var year = d.getFullYear();
        var month = d.getMonth() + 1;
        if (Math.abs(months) > 12) {
            months = months % 12;
        };
        if (months != 0) {
            if (month + months > 12) {
                year++;
                month = (month + months) % 12;
            } else if (month + months < 1) {
                year--;
                month = 12 + month + months;
            } else {
                month = month + months;
            };
        };
        month = month < 10 ? "0" + month: month;
        var date = d.getDate();
        var firstday = year + "-" + month + "-" + "01";
        var lastday = "";
        if (month == "01" || month == "03" || month == "05" || month == "07" || month == "08" || month == "10" || month == "12") {
            lastday = year + "-" + month + "-" + 31;
        } else if (month == "02") {
            if ((year % 4 == 0 && year % 100 != 0) || (year % 100 == 0 && year % 400 == 0)) {
                lastday = year + "-" + month + "-" + 29;
    } else {
                lastday = year + "-" + month + "-" + 28;
            };
        } else {
            lastday = year + "-" + month + "-" + 30;
        };
        var day = "";
        if (type == "s") {
            day = firstday;
        } else {
            day = lastday;
        };
        return day;
    },
    //4、得到今年、去年、明年的开始、结束日期
    //type为字符串类型，有两种选择，"s"代表开始,"e"代表结束，dates为数字类型，不传或0代表今年，-1代表去年，1代表明年
    getYear(type, dates) {
        var dd = new Date();
        var n = dates || 0;
        var year = dd.getFullYear() + Number(n);
        if (type == "s") {
            var day = year + "-01-01";
        };
        if (type == "e") {
            var day = year + "-12-31";
        };
        if (!type) {
            var day = year + "-01-01/" + year + "-12-31";
        };
        return day;
    },
    //5、得到本学期: 
    //"s"代表开始,"e"代表结束，dates为数字类型，2-8月份为下学期
    getTerm(type,dates){　
       let nowYear = new Date().getFullYear();
       let prevYear = new Date().getFullYear() - 1;
       let nextYear = new Date().getFullYear() + 1;

        if(type === 's'){
          if(dates < 2){
            return prevYear+"-09-01";
          }else if (dates > 8){
            return nowYear+"-09-01";
          }else{
            return nowYear+"-02-01";
          }
        }
        if(type === 'e'){
            if(dates < 2){
              return nowYear+"-01-31";
            }else if (dates > 8){
              return nextYear+"-01-31";
            }else{
              return nowYear+"-08-31";
            }
        }
    　 
    }　　 

}

export default getDateFn;

这是公共方式，引入的时候时引入对象

<template>
  <div>  </div>
</template>
<script>
import getDateFn from '@/utils/getDateFn'
export default {
created() {
	console.log('今日日期',getDateFn.getDate());
	console.log('本周开始日期',getDateFn.getMonday('s'));
	console.log('本周结束日期',getDateFn.getMonday('e'));
	console.log('本月开始日期',getDateFn.getMonth('s',0));
	console.log('本月结束日期',getDateFn.getMonth('e',0));
	console.log('本学期开始日期',getDateFn.getTerm('s',new Date().getMonth() + 1));
	console.log('本学期结束日期',getDateFn.getTerm('e',new Date().getMonth() + 1));
}
}