js控制在页面显示时间，每秒更新一次

setInterval("showTime()",1000);
function showTime(){
        var date     = new Date();
        var year     = date.getFullYear();    //获取完整的年份(4位,1970-????)
        var month     = date.getMonth() + 1;   //获取当前月份(0-11,0代表1月)
        var da         = date.getDate();        //获取当前日(1-31)
        var day     = date.getDay();         //获取当前星期X(0-6,0代表星期天)        
        var hour     = date.getHours();       //获取当前小时数(0-23)
        var minute     = date.getMinutes();     //获取当前分钟数(0-59)
        var seconds = date.getSeconds();     //获取当前秒数(0-59)
        var dateString = year + "年" + checkNum(month) + " 月" + checkNum(da) +"日";
        var timeString = checkNum(hour) + ":" + checkNum(minute) + ":" + checkNum(seconds) + "";
        var dayString = "星期"+day;
        $('#dateString').text(dateString);
        $('#timeString').text(timeString);
        $('#dayString').text(dayString);
    }
    function checkNum(num){
        if(num < 10){
            return "0" + num; 
        }
        return num;
    }

效果如下：