如何把时间长度(秒)转换成可读的形式

function getDuration(lasttime) {
    var seconds = ( Date.now() / 1000 | 0 ) - lasttime;
    if (seconds > 60*2) {
        if (seconds > 3600*2) {
            if (seconds > 3600*24*2) {
                if (seconds > 3600*24*7*2) {
                    if (seconds > 3600*24*30*2) {
                        if (seconds > 3600*24*365*2) {
                            return (seconds / (3600*24*365) | 0) + " years";
                        }
                        return (seconds / (3600*24*30) | 0) + " months";
                    }
                    return (seconds / (3600*24*7) | 0) + " weeks";
                }
                return (seconds / (3600*24) | 0) + " days";
            }
            return (seconds / 3600 | 0) + " hours";
        }
        return (seconds / 60 | 0) + " minutes";
    }
    return (seconds) + " seconds";
}