js获取指定日期

			//计算日期 多少月前
			countdate(before) {
				let date = new Date();
				date.setMonth(date.getMonth() - before);
				let fullYear = date.getFullYear();
				let month = date.getMonth() + 1;
				let month2 = date.getMonth();
				let strDate = date.getDate();
				if (month >= 1 && month <= 9) {
					month = "0" + month;
				}
				if (strDate >= 0 && strDate <= 9) {
					strDate = "0" + strDate;
				}
				return fullYear + "" + month + "" + strDate;
			}
			//获取当前时间之前或之后多少天
			getDateStr(AddDayCount) {
				var dd = new Date();
				dd.setDate(dd.getDate() + AddDayCount);//获取AddDayCount天后的日期
				var y = dd.getFullYear();
				var m = (dd.getMonth() + 1) < 10 ? "0" + (dd.getMonth() + 1) : (dd.getMonth()+1);//获取当前月份的日期，不足10补0
				var d = dd.getDate() < 10 ? "0" + dd.getDate() : dd.getDate();//获取当前几号，不足10补0
				return y + "" + m + "" + d;
			}