/**
* @desc：日期计算类
* @author [lee] <[]>
* @param dur 增量 如：+1day -5 year 6months
* @param time 传入时间 支持格式 1、y-m-d H:i:s 2、1111111111
* @return 字符串 如：2018-01-01 00:00:00
*/
function dateadd(dur,time = false){
/*
 @desc：主方法，执行转换
 */
this.getdate = function(){
    var test_year = /(-)?\d+(\s)?year(s)?/.exec(dur)
    var test_month = /(-)?\d+(\s)?month(s)?/.exec(dur)
    var test_day = /(-)?\d+(\s)?day(s)?/.exec(dur)
    var test_hour = /(-)?\d+(\s)?hour(s)?/.exec(dur)
    var test_minute = /(-)?\d+(\s)?minute(s)?/.exec(dur)
    var test_second = /(-)?\d+(\s)?second(s)?/.exec(dur)
    test_year = (!test_year)?0:parseInt(test_year[0])
    test_month = (!test_month)?0:parseInt(test_month[0])
    test_day = (!test_day)?0:parseInt(test_day[0])
    test_hour = (!test_hour)?0:parseInt(test_hour[0])
    test_minute = (!test_minute)?0:parseInt(test_minute[0])
    test_second = (!test_second)?0:parseInt(test_second[0])
    var outtime
    if(time){
        if(((typeof(time)=='string') || (time instanceof String)) && (/^\d{4}(-\d{2}(-\d{2})?)?$/.test(time))){
            outtime = new Date(time)
            outtime.setFullYear(parseInt(outtime.getFullYear()) + test_year)
            outtime.setMonth(parseInt(outtime.getMonth()) + test_month)
            outtime.setDate(parseInt(outtime.getDate()) + test_day)
            outtime.setHours(parseInt(outtime.getHours()) + test_hour)
            outtime.setMinutes(parseInt(outtime.getMinutes()) + test_minute)
            outtime.setSeconds(parseInt(outtime.getSeconds()) + test_second)
            var month = this.parsetime(parseInt(outtime.getUTCMonth())+1)
            var date = this.parsetime(parseInt(outtime.getUTCDate()))
            var hour = this.parsetime(parseInt(outtime.getUTCHours()))
            var minute = this.parsetime(parseInt(outtime.getUTCMinutes()))
            var second = this.parsetime(parseInt(outtime.getUTCSeconds()))
        }else{
            outtime = new Date(time*1000)
            outtime.setFullYear(parseInt(outtime.getFullYear()) + test_year)
            outtime.setMonth(parseInt(outtime.getMonth()) + test_month)
            outtime.setDate(parseInt(outtime.getDate()) + test_day)
            outtime.setHours(parseInt(outtime.getHours()) + test_hour)
            outtime.setMinutes(parseInt(outtime.getMinutes()) + test_minute)
            outtime.setSeconds(parseInt(outtime.getSeconds()) + test_second)
            var month = this.parsetime(parseInt(outtime.getMonth())+1)
            var date = this.parsetime(parseInt(outtime.getDate()))
            var hour = this.parsetime(parseInt(outtime.getHours()))
            var minute = this.parsetime(parseInt(outtime.getMinutes()))
            var second = this.parsetime(parseInt(outtime.getSeconds()))
        }
    }else{
        outtime = new Date()
        outtime.setFullYear(parseInt(outtime.getFullYear()) + test_year)
        outtime.setMonth(parseInt(outtime.getMonth()) + test_month)
        outtime.setDate(parseInt(outtime.getDate()) + test_day)
        outtime.setHours(parseInt(outtime.getHours()) + test_hour)
        outtime.setMinutes(parseInt(outtime.getMinutes()) + test_minute)
        outtime.setSeconds(parseInt(outtime.getSeconds()) + test_second)
        var month = this.parsetime(parseInt(outtime.getMonth())+1)
        var date = this.parsetime(parseInt(outtime.getDate()))
        var hour = this.parsetime(parseInt(outtime.getHours()))
        var minute = this.parsetime(parseInt(outtime.getMinutes()))
        var second = this.parsetime(parseInt(outtime.getSeconds()))
    }
    var year = outtime.getFullYear()
    var ret = year+'-'+month+'-'+date+' '+hour+':'+minute+':'+second
    return ret
}
/*
 @desc：内部方法，不足10补0
 */
this.parsetime = function(input){
    var ret
    if(input >= 0 && input < 10){
        ret = '0'+input
    }else{
        ret = input
    }
    return ret
}
}
var dateadd = new dateadd('+3hour +2year-5months','2018-05-08')
var ret = dateadd.getdate()
console.log(ret)

参见：date_add函数

参见：DATE_ADD函数