对时间进行操作 加减 XXX天

date:要操作的时间目标

days: 要加减的天数时间

addDate: function(date, days) {

if (date == '') {

return ''

};

if (days == undefined || days == '') {

days = 0;

}

var timebox = new Date(date);

timebox.setDate(timebox.getDate() + days);

var month = timebox.getMonth() + 1;

var day = timebox.getDate();

return timebox.getFullYear() + '-' + month + '-' + day;

},