日期加减

JavaScript：
    function addDate(date, days) { //格式:addDate(‘2017-1-11‘, -20)
        var d = new Date(Date.parse(date.replace(/-/g, "/")));//兼容性处理
        d.setDate(d.getDate() + days);
        var m = d.getMonth() + 1;
        var res = d.getFullYear() + ‘/‘ + m + ‘/‘ + d.getDate();
        return new Date(res).Format(‘yyyy-MM-dd‘);
    }
java：
    private Date add(Date date, int amount) {
        if (date == null) {
            final Calendar c = Calendar.getInstance();
            c.setTime(date);
            c.add(Calendar.DAY_OF_MONTH, amount);
            return c.getTime();
        }
        return date;
    }
 
addYears            Calendar.YEAR
addMonths            Calendar.MONTH
addWeeks            Calendar.WEEK_OF_YEAR
addDays                Calendar.DAY_OF_MONTH
    
addHours            Calendar.HOUR_OF_DAY
addMinutes            Calendar.MINUTE
addSeconds            Calendar.SECOND
addMilliseconds        Calendar.MILLISECOND