封装三个关于date的方法

1.获取日期并给其补零

var myTime=function(i,j){
        //创建Date（）对象
        var date = new Date();
          //获取年月日时分秒
        var year= bl(date.getFullYear());
        var month= bl(date.getMonth()+1);
        var date= bl(date.getDate());
        var hours= bl(date.getHours());
        var minutes=bl( date.getMinutes());
        var seconds= bl(date.getSeconds());
        return year+"-"+month+"-"+date+" "+hours+":"+minutes+":"+seconds;

    }
    function bl(n){
        //定义给时间补零的方法
        if(n>10){
            return n;
        }else{
            return "0"+n;
        }
        //或者用三目运算符
        //n>10?return n:return "0"+n
    }

2.获取星期几的方法

function getWeek() {
        //创建日期对象
        var date = new Date();
        //获取星期，0为星期天，其他的一一对应
        var week = date.getDay();
        var res="";
        switch(week){
            case 0:  res="星期日";
            break;
            case 1:  res="星期一";
            break;
            case 2:  res="星期二";
            break;
            case 3:  res="星期三";
            break;
            case 4:  res="星期四";
            break;
            case 5:  res="星期五";
            break;
            case 6:  res="星期六";
            break;
        }
        return res;
    }

3.动态倒计时

function countdown(holiday,time){
        var nowdate=new Date();
        var targetdate = new Date(time);
        var ms=parseInt(targetdate.getTime()-nowdate.getTime());//获取目标事件与当前事件所差的毫秒值
        var s = parseInt( ms/1000%60);//获取秒
        var m = parseInt(ms/1000/60%60);//获取分钟
        var h = parseInt(ms/1000/60/60%24);//获取小时
        var d = parseInt(ms/1000/60/60/24);//获取天数
        return "距离"+holiday+"还有："+d+"天，"+h+"小时，"+m+"分钟，"+s+"秒；";
    }
    setInterval(function(){document.body.innerHTML=countdown("国庆","2022-10-1 00:00:00")},1000);
</script>