在js里面获取当前时间的前六个月

   var time = new Date();
    time.setTime(time.getTime());
    var s2 = time.getFullYear()+"-" + (time.getMonth()+1) + "-" + time.getDate();
    var monthNum=6; //要减的月数(6)自己定义
    var dateArr = s2.split('-'); //s2当前时间
    var year = dateArr[0]; //获取当前日期的年份
    var month = dateArr[1]; //获取当前日期的月份
    var day = dateArr[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) - monthNum;
    if (month2 <=0) {
        year2 = parseInt(year2) - parseInt(month2 / 12 == 0 ? 1 : parseInt(month2) / 12);
        month2 = 12 - (Math.abs(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;