web页面显示当前系统时间并定时刷新

function showCurrentDate(){
    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.getYear()+1900;
    month = today.getMonth()+1;
    if(month<10){
        month="0"+month;
    }
    date = today.getDate();
    if(date<10){
        date="0"+date;
    }
    hour = today.getHours();
    if(hour<10){
        hour="0"+hour;
    }
    minute =today.getMinutes();
    if(minute<10){
        minute="0"+minute;
    }
    second = today.getSeconds();
    if(second<10){
        second="0"+second;
    }
    document.getElementById('currentDate').innerHTML = year + ":" + month + ":" + date + " " + strDate +" " + hour + ":" + minute + ":" + second; //显示时间
    window.setTimeout('showCurrentDate()',1000);
}