JS实现实时显示时间

<p class="col-xs-12 col-sm-6">

      <i class="fa fa-plus-square-o" aria-hidden="true"></i>

      <span id="current-time"></span>
</p>

/*实时显示时间*/

 function showtime(){

    var today,hour,second,minute,year,month,date;

    var strDate ;

    today=new Date();

    var n_day = today.getDay();

    switch (n_day){

        case 0:{

          strDate = "星期日"

        }break;

        case 1:{

          strDate = "星期一"

        }break;

        case 2:{

          strDate ="星期二"

        }break;

        case 3:{

          strDate = "星期三"

        }break;

        case 4:{

          strDate = "星期四"

        }break;

        case 5:{

          strDate = "星期五"

        }break;

        case 6:{

          strDate = "星期六"

        }break;

        case 7:{

          strDate = "星期日"

        }break;

    }

    year = today.getFullYear();

    month = today.getMonth()+1;

    date = today.getDate();

    hour = today.getHours();

    minute =today.getMinutes();

    second = today.getSeconds();

 

    if (month >= 1 && month <= 9) {

        month = "0" + month;

    }

    if (date >= 0 && date <= 9) {

        date = "0" + date;

    }

    if (hour >= 0 && hour <= 9) {

        hour = "0" + hour;

    }

    if (minute >= 0 && minute <= 9) {

        minute = "0" + minute;

    }

    if (second >= 0 && second <= 9) {

        second = "0" + second;

    }

    document.getElementById('current-time').innerHTML ="当前时间："+ year + "年" + month + "月" + date + "日" +"  "+ strDate +"   " + hour + ":" + minute + ":" + second; //显示时间

    setTimeout("showtime();", 1000); //设定函数自动执行时间为 1000 ms(1 s)

}