刚好项目需要这样一个功能，顺便共享出来给大家玩耍。

https://github.com/jaywcjlove/date.js

例子：

dateDiff(Timestamp,now Timestamp)
Timestamp:毫秒

dateDiff(1411430400000,1421313395359)
//=>"3个月前"

dateDiff(new Date('1987-04-03').getTime())
//=>"28年前"

源码：

;(function(window){
    /**
     * [dateDiff 算时间差]
     * @param  {[type=Number]} hisTime [历史时间戳，必传]
     * @param  {[type=Number]} nowTime [当前时间戳，不传将获取当前时间戳]
     * @return {[string]}         [string]
     */
    var dateDiff = function(hisTime,nowTime){
        var now =nowTime?nowTime:new Date().getTime(),
            diffValue = now - hisTime,
            result='',
            minute = 1000 * 60,
            hour = minute * 60,
            day = hour * 24,
            halfamonth = day * 15,
            month = day * 30,
            year = month * 12,
            
            _year = diffValue/year,
            _month =diffValue/month,
            _week =diffValue/(7*day),
            _day =diffValue/day,
            _hour =diffValue/hour,
            _min =diffValue/minute;
            
            if(_year>=1) result=parseInt(_year) + "年前";
            else if(_month>=1) result=parseInt(_month) + "个月前";
            else if(_week>=1) result=parseInt(_week) + "周前";
            else if(_day>=1) result=parseInt(_day) +"天前";
            else if(_hour>=1) result=parseInt(_hour) +"个小时前";
            else if(_min>=1) result=parseInt(_min) +"分钟前";
            else result="刚刚";
            return result;
    }
    window.dateDiff = dateDiff
})(window);

改成了型参数，应该是这样吧

;(function(window){
    /**
     * [dateDiff 算时间差]
     * @param  {[type=Number]} hisTime [历史时间戳，必传]
     * @param  {[type=Number]} nowTime [当前时间戳，不传将获取当前时间戳]
     * @return {[string]}         [string]
     */
    var dateDiff = function(hisTime,nowTime){
        if(!arguments.length) return '';
        var arg = arguments,
            now =arg[1]?arg[1]:new Date().getTime(),
            diffValue = now - arg[0],
            result='',

            minute = 1000 * 60,
            hour = minute * 60,
            day = hour * 24,
            halfamonth = day * 15,
            month = day * 30,
            year = month * 12,

            _year = diffValue/year,
            _month =diffValue/month,
            _week =diffValue/(7*day),
            _day =diffValue/day,
            _hour =diffValue/hour,
            _min =diffValue/minute;

            if(_year>=1) result=parseInt(_year) + "年前";
            else if(_month>=1) result=parseInt(_month) + "个月前";
            else if(_week>=1) result=parseInt(_week) + "周前";
            else if(_day>=1) result=parseInt(_day) +"天前";
            else if(_hour>=1) result=parseInt(_hour) +"个小时前";
            else if(_min>=1) result=parseInt(_min) +"分钟前";
            else result="刚刚";
            return result;
    }
    window.dateDiff = dateDiff
})(window);