JavaScript获取上月与下月日期函数

         function getPreMonth(date) {
            var arr = date.split('-');
            var year = arr[0]; //获取当前日期的年份  
            var month = arr[1]; //获取当前日期的月份  
            //var day = arr[2]; //获取当前日期的日  
            //var days = new Date(year, month, 0);
            //days = days.getDate(); //获取当前日期中月的天数  
            var year2 = year;
            var month2 = parseInt(month) - 1;
            if (month2 == 0) {
                year2 = parseInt(year2) - 1;
                month2 = 12;
            }
            //var day2 = day;
            //var days2 = new Date(year2, month2, 0);
            //days2 = days2.getDate();
            //if (day2 > days2) {
                //day2 = days2;
            //}
            if (month2 < 10) {
                month2 = '0' + month2;
            }
            var t2 = year2 + ""+ month2;//  + '-' + day2;
            return t2;
        }

        function getNextMonth(date) {
            var arr = date.split('-');
            var year = arr[0]; //获取当前日期的年份
            var month = arr[1]; //获取当前日期的月份

            //var day = arr[2]; //获取当前日期的日
            //var days = new Date(year, month, 0);
            //days = days.getDate(); //获取当前日期中的月的天数
            var year2 = year;
            var month2 = parseInt(month) + 1;
            if (month2 == 13) {
                year2 = parseInt(year2) + 1;
                month2 = 1;
            }
            //var day2 = day;
            //var days2 = new Date(year2, month2, 0);
            //days2 = days2.getDate();
            //if (day2 > days2) {
                //day2 = days2;
            //}
            if (month2 < 10) {
                month2 = '0' + month2;
            }

            var t2 = year2 + '-' + month2;//  + '-' + day2;
            return t2;
        }






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