自定义一周的开始和结束，计算日期所在月的周数、所在月第几周、所在周的日期范围

• 一. 方法使用
• 二. 实现案例

一. 方法使用

根据月开始日期星期几、月结束日期星期几，计算始周、末周占月的天数（每周周期段：上周六 —— 本周五）

getStrEndDay(str_week, end_week) {// 始周占月的天数：开始周几(str_week) 距离 结束(周五) 有几天let str_num = 0;switch (str_week) {case 1:str_num = 5;break;case 2:str_num = 4;break;case 3:str_num = 3;break;case 4:str_num = 2;break;case 5:str_num = 1;break;case 6:str_num = 7;break;case 7:str_num = 6;break;}// 末周占月的天数：开始(周六) 距离 结束周几(end_week) 有几天let end_num = 0;switch (end_week) {case 1:end_num = 3;break;case 2:end_num = 4;break;case 3:end_num = 5;break;case 4:end_num = 6;break;case 5:end_num = 7;break;case 6:end_num = 1;break;case 0:end_num = 2;break;}return { str_num, end_num };
}

根据年月，获取每月有几周

getWeekCount(year, month) {// 获取天数var day_num = new Date(year, month, 0).getDate();// 该月第一天、最后一天const str_day = new Date().setFullYear(year, month - 1, 1);const end_day = new Date().setFullYear(year, month, 0);//该月第一周、最后一周const str_week = new Date(str_day).getDay();const end_week = new Date(end_day).getDay();// 该月减去第一周、最后一周的天数const numRes = this.getStrEndDay(str_week, end_week);const oth_day = day_num - numRes.end_num - numRes.str_num;// 总周数let week_num = oth_day / 7;if (numRes.str_num == 7) {week_num += 1;}if (numRes.end_num != 0) {week_num += 1;}return week_num;
}

根据年月日获取当前周

getCurWeek(year, month, day) {// 该月第一天、最后一天const str_day = new Date().setFullYear(year, month - 1, 1);const end_day = new Date().setFullYear(year, month, 0);//该月第一周、最后一周const str_week = new Date(str_day).getDay();const end_week = new Date(end_day).getDay();// 该月减去第一周的天数const numRes = this.getStrEndDay(str_week, end_week);const oth_day = day - numRes.str_num;// 第几周let cur_week = Math.ceil(oth_day / 7);if (numRes.str_num == 7) {cur_week += 1;}return cur_week;
}

根据年、月、周获取周的日期

getWeekTime(year, month, week) {// 获取天数var day_num = new Date(year, month, 0).getDate();// 该月第一天、最后一天const str_day = new Date().setFullYear(year, month - 1, 1);const end_day = new Date().setFullYear(year, month, 0);//该月第一周、最后一周const str_week = new Date(str_day).getDay();const end_week = new Date(end_day).getDay();const numRes = this.getStrEndDay(str_week, end_week);// 该周开始、结束日期let str_time = (week - 1) * 7 + 1;let end_time = week * 7;if (numRes.str_num != 7) {str_time += numRes.str_num;end_time += numRes.str_num;}let mm = Number(month);mm = mm < 10 ? "0" + mm : mm;str_time = str_time < 10 ? "0" + str_time : str_time;end_time = end_time < 10 ? "0" + end_time : end_time;let strDate = year + "-" + mm + "-" + str_time;let endDate = year + "-" + mm + "-" + end_time;if (Number(end_time) > day_num) {let mm1 = Number(mm) + 1 < 10 ? "0" + (Number(mm) + 1) : Number(mm) + 1;let last_num = Number(end_time) - day_num;last_num = last_num < 10 ? "0" + last_num : last_num;endDate = year + "-" + mm1 + "-" + last_num;}return {strDate,endDate};
}

二. 实现案例