function timeago(dateTimeStamp){ 
 //dateTimeStamp是一个时间毫秒，注意时间戳是秒的形式，在这个毫秒的基础上除以1000，就是十位数的时间戳。13位数的都是时间毫秒。
 var minute = 1000 * 60;
 //把分，时，天，周，半个月，一个月用毫秒表示
 var hour = minute * 60;
 var day = hour * 24;
 var week = day * 7;
 var halfamonth = day * 15;
 var month = day * 30;
 var now = new Date().getTime(); 
 //获取当前时间毫秒
 console.log(now)
 var diffValue = now - dateTimeStamp;
 //时间差
 if(diffValue < 0){
 return;
 }
 var minC = diffValue/minute; 
 //计算时间差的分，时，天，周，月
 var hourC = diffValue/hour;
 var dayC = diffValue/day;
 var weekC = diffValue/week;
 var monthC = diffValue/month;
 if(monthC >= 1 && monthC <= 3){
 result = " " + parseInt(monthC) + "月前"
 }else if(weekC >= 1 && weekC <= 3){
 result = " " + parseInt(weekC) + "周前"
 }else if(dayC >= 1 && dayC <= 6){
 result = " " + parseInt(dayC) + "天前"
 }else if(hourC >= 1 && hourC <= 23){
 result = " " + parseInt(hourC) + "小时前"
 }else if(minC >= 1 && minC <= 59){
 result =" " + parseInt(minC) + "分钟前"
 }else if(diffValue >= 0 && diffValue <= minute){
 result = "刚刚"
 }else {
 var datetime = new Date();
 datetime.setTime(dateTimeStamp);
 var Nyear = datetime.getFullYear();
 var Nmonth = datetime.getMonth() + 1 < 10 ? "0" + (datetime.getMonth() + 1) : datetime.getMonth() + 1;
 var Ndate = datetime.getDate() < 10 ? "0" + datetime.getDate() : datetime.getDate();
 var Nhour = datetime.getHours() < 10 ? "0" + datetime.getHours() : datetime.getHours();
 var Nminute = datetime.getMinutes() < 10 ? "0" + datetime.getMinutes() : datetime.getMinutes();
 var Nsecond = datetime.getSeconds() < 10 ? "0" + datetime.getSeconds() : datetime.getSeconds();
 result = Nyear + "-" + Nmonth + "-" + Ndate
 }
 return result;
}

示例：
   var time=timeago(1519181561000);
   alert(time);   输出 11小时之前