话不多说，直接上代码。

function getWeek(date) {	var week;	if(date.getDay() == 0) week = "星期日"	if(date.getDay() == 1) week = "星期一"	if(date.getDay() == 2) week = "星期二"	if(date.getDay() == 3) week = "星期三"	if(date.getDay() == 4) week = "星期四"	if(date.getDay() == 5) week = "星期五"	if(date.getDay() == 6) week = "星期六"	return week;}console.log(getWeek(new Date("2017-08-21")));

　　

function getDateTimeBefor(publishtime) {        var currTime = Date.parse(new Date());;        var l = parseInt(currTime) - parseInt(publishtime);        // 少于一分钟        var time = l / 1000;        if (time < 60) {            return "刚刚";        }        // 秒转分钟        var minuies = time / 60;        if (minuies < 60) {            return Math.floor(minuies) + "分钟前";        }        // 秒转小时        var hours = time / 3600;        if (hours < 24) {            return Math.floor(hours) + "小时前";        }        //秒转天数        var days = time / 3600 / 24;        if (days < 30) {            return Math.floor(days) + "天前";        }        //秒转月        var months = time / 3600 / 24 / 30;        if (months < 12) {            return Math.floor(months) + "月前";        }        //秒转年        var years = time / 3600 / 24 / 30 / 12;        return Math.floor(years) + "年前";    }