var myDate = new Date();
myDate.getYear();        //获取当前年份(2位)
myDate.getFullYear();    //获取完整的年份(4位,1970-????)
myDate.getMonth();       //获取当前月份(0-11,0代表1月)
myDate.getDate();        //获取当前日(1-31)
myDate.getDay();         //获取当前星期X(0-6,0代表星期天)
myDate.getTime();        //获取当前时间(从1970.1.1开始的毫秒数)
myDate.getHours();       //获取当前小时数(0-23)
myDate.getMinutes();     //获取当前分钟数(0-59)
myDate.getSeconds();     //获取当前秒数(0-59)
myDate.getMilliseconds();    //获取当前毫秒数(0-999)
myDate.toLocaleDateString();     //获取当前日期
var mytime=myDate.toLocaleTimeString();     //获取当前时间
myDate.toLocaleString( );        //获取日期与时间

//---------------------------------------------------  
// 判断闰年  
//---------------------------------------------------  
Date.prototype.isLeapYear = function()   
{   
    return (0==this.getYear()%4&&((this.getYear()%100!=0)||(this.getYear()%400==0)));   
}   
  
//---------------------------------------------------  
// 日期格式化  
// 格式 YYYY/yyyy/YY/yy 表示年份  
// MM/M 月份  
// W/w 星期  
// dd/DD/d/D 日期  
// hh/HH/h/H 时间  
// mm/m 分钟  
// ss/SS/s/S 秒  
//---------------------------------------------------  
Date.prototype.Format = function(formatStr)   
{   
    var str = formatStr;   
    var Week = [\'日\',\'一\',\'二\',\'三\',\'四\',\'五\',\'六\'];  
  
    str=str.replace(/yyyy|YYYY/,this.getFullYear());   
    str=str.replace(/yy|YY/,(this.getYear() % 100)>9?(this.getYear() % 100).toString():\'0\' + (this.getYear() % 100));   
  
    str=str.replace(/MM/,this.getMonth()>9?this.getMonth().toString():\'0\' + this.getMonth());   
    str=str.replace(/M/g,this.getMonth());   
  
    str=str.replace(/w|W/g,Week[this.getDay()]);   
  
    str=str.replace(/dd|DD/,this.getDate()>9?this.getDate().toString():\'0\' + this.getDate());   
    str=str.replace(/d|D/g,this.getDate());   
  
    str=str.replace(/hh|HH/,this.getHours()>9?this.getHours().toString():\'0\' + this.getHours());   
    str=str.replace(/h|H/g,this.getHours());   
    str=str.replace(/mm/,this.getMinutes()>9?this.getMinutes().toString():\'0\' + this.getMinutes());   
    str=str.replace(/m/g,this.getMinutes());   
  
    str=str.replace(/ss|SS/,this.getSeconds()>9?this.getSeconds().toString():\'0\' + this.getSeconds());   
    str=str.replace(/s|S/g,this.getSeconds());   
  
    return str;   
}   
  
//+---------------------------------------------------  
//| 求两个时间的天数差 日期格式为 YYYY-MM-dd   
//+---------------------------------------------------  
function daysBetween(DateOne,DateTwo)  
{   
    var OneMonth = DateOne.substring(5,DateOne.lastIndexOf (\'-\'));  
    var OneDay = DateOne.substring(DateOne.length,DateOne.lastIndexOf (\'-\')+1);  
    var OneYear = DateOne.substring(0,DateOne.indexOf (\'-\'));  
  
    var TwoMonth = DateTwo.substring(5,DateTwo.lastIndexOf (\'-\'));  
    var TwoDay = DateTwo.substring(DateTwo.length,DateTwo.lastIndexOf (\'-\')+1);  
    var TwoYear = DateTwo.substring(0,DateTwo.indexOf (\'-\'));  
  
    var cha=((Date.parse(OneMonth+\'/\'+OneDay+\'/\'+OneYear)- Date.parse(TwoMonth+\'/\'+TwoDay+\'/\'+TwoYear))/86400000);   
    return Math.abs(cha);  
}  
  
  
//+---------------------------------------------------  
//| 日期计算  
//+---------------------------------------------------  
Date.prototype.DateAdd = function(strInterval, Number) {   
    var dtTmp = this;  
    switch (strInterval) {   
        case \'s\' :return new Date(Date.parse(dtTmp) + (1000 * Number));  
        case \'n\' :return new Date(Date.parse(dtTmp) + (60000 * Number));  
        case \'h\' :return new Date(Date.parse(dtTmp) + (3600000 * Number));  
        case \'d\' :return new Date(Date.parse(dtTmp) + (86400000 * Number));  
        case \'w\' :return new Date(Date.parse(dtTmp) + ((86400000 * 7) * Number));  
        case \'q\' :return new Date(dtTmp.getFullYear(), (dtTmp.getMonth()) + Number*3, dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());  
        case \'m\' :return new Date(dtTmp.getFullYear(), (dtTmp.getMonth()) + Number, dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());  
        case \'y\' :return new Date((dtTmp.getFullYear() + Number), dtTmp.getMonth(), dtTmp.getDate(), dtTmp.getHours(), dtTmp.getMinutes(), dtTmp.getSeconds());  
    }  
}  
  
//+---------------------------------------------------  
//| 比较日期差 dtEnd 格式为日期型或者有效日期格式字符串  
//+---------------------------------------------------  
Date.prototype.DateDiff = function(strInterval, dtEnd) {   
    var dtStart = this;  
    if (typeof dtEnd == \'string\' )//如果是字符串转换为日期型  
    {   
        dtEnd = StringToDate(dtEnd);  
    }  
    switch (strInterval) {   
        case \'s\' :return parseInt((dtEnd - dtStart) / 1000);  
        case \'n\' :return parseInt((dtEnd - dtStart) / 60000);  
        case \'h\' :return parseInt((dtEnd - dtStart) / 3600000);  
        case \'d\' :return parseInt((dtEnd - dtStart) / 86400000);  
        case \'w\' :return parseInt((dtEnd - dtStart) / (86400000 * 7));  
        case \'m\' :return (dtEnd.getMonth()+1)+((dtEnd.getFullYear()-dtStart.getFullYear())*12) - (dtStart.getMonth()+1);  
        case \'y\' :return dtEnd.getFullYear() - dtStart.getFullYear();  
    }  
}  
  
//+---------------------------------------------------  
//| 日期输出字符串，重载了系统的toString方法  
//+---------------------------------------------------  
Date.prototype.toString = function(showWeek)  
{   
    var myDate= this;  
    var str = myDate.toLocaleDateString();  
    if (showWeek)  
    {   
        var Week = [\'日\',\'一\',\'二\',\'三\',\'四\',\'五\',\'六\'];  
        str += \' 星期\' + Week[myDate.getDay()];  
    }  
    return str;  
}  
  
//+---------------------------------------------------  
//| 日期合法性验证  
//| 格式为：YYYY-MM-DD或YYYY/MM/DD  
//+---------------------------------------------------  
function IsValidDate(DateStr)   
{   
    var sDate=DateStr.replace(/(^\s+|\s+$)/g,\'\'); //去两边空格;   
    if(sDate==\'\') return true;   
    //如果格式满足YYYY-(/)MM-(/)DD或YYYY-(/)M-(/)DD或YYYY-(/)M-(/)D或YYYY-(/)MM-(/)D就替换为\'\'   
    //数据库中，合法日期可以是:YYYY-MM/DD(2003-3/21),数据库会自动转换为YYYY-MM-DD格式   
    var s = sDate.replace(/[\d]{ 4,4 }[\-/]{ 1 }[\d]{ 1,2 }[\-/]{ 1 }[\d]{ 1,2 }/g,\'\');   
    if (s==\'\') //说明格式满足YYYY-MM-DD或YYYY-M-DD或YYYY-M-D或YYYY-MM-D   
    {   
        var t=new Date(sDate.replace(/\-/g,\'/\'));   
        var ar = sDate.split(/[-/:]/);   
        if(ar[0] != t.getYear() || ar[1] != t.getMonth()+1 || ar[2] != t.getDate())   
        {   
            //alert(\'错误的日期格式！格式为：YYYY-MM-DD或YYYY/MM/DD。注意闰年。\');   
            return false;   
        }   
    }   
    else   
    {   
        //alert(\'错误的日期格式！格式为：YYYY-MM-DD或YYYY/MM/DD。注意闰年。\');   
        return false;   
    }   
    return true;   
}   
  
//+---------------------------------------------------  
//| 日期时间检查  
//| 格式为：YYYY-MM-DD HH:MM:SS  
//+---------------------------------------------------  
function CheckDateTime(str)  
{   
    var reg = /^(\d+)-(\d{ 1,2 })-(\d{ 1,2 }) (\d{ 1,2 }):(\d{ 1,2 }):(\d{ 1,2 })$/;   
    var r = str.match(reg);   
    if(r==null)return false;   
    r[2]=r[2]-1;   
    var d= new Date(r[1],r[2],r[3],r[4],r[5],r[6]);   
    if(d.getFullYear()!=r[1])return false;   
    if(d.getMonth()!=r[2])return false;   
    if(d.getDate()!=r[3])return false;   
    if(d.getHours()!=r[4])return false;   
    if(d.getMinutes()!=r[5])return false;   
    if(d.getSeconds()!=r[6])return false;   
    return true;   
}   
  
//+---------------------------------------------------  
//| 把日期分割成数组  
//+---------------------------------------------------  
Date.prototype.toArray = function()  
{   
    var myDate = this;  
    var myArray = Array();  
    myArray[0] = myDate.getFullYear();  
    myArray[1] = myDate.getMonth();  
    myArray[2] = myDate.getDate();  
    myArray[3] = myDate.getHours();  
    myArray[4] = myDate.getMinutes();  
    myArray[5] = myDate.getSeconds();  
    return myArray;  
}  
  
//+---------------------------------------------------  
//| 取得日期数据信息  
//| 参数 interval 表示数据类型  
//| y 年 m月 d日 w星期 ww周 h时 n分 s秒  
//+---------------------------------------------------  
Date.prototype.DatePart = function(interval)  
{   
    var myDate = this;  
    var partStr=\'\';  
    var Week = [\'日\',\'一\',\'二\',\'三\',\'四\',\'五\',\'六\'];  
    switch (interval)  
    {   
        case \'y\' :partStr = myDate.getFullYear();break;  
        case \'m\' :partStr = myDate.getMonth()+1;break;  
        case \'d\' :partStr = myDate.getDate();break;  
        case \'w\' :partStr = Week[myDate.getDay()];break;  
        case \'ww\' :partStr = myDate.WeekNumOfYear();break;  
        case \'h\' :partStr = myDate.getHours();break;  
        case \'n\' :partStr = myDate.getMinutes();break;  
        case \'s\' :partStr = myDate.getSeconds();break;  
    }  
    return partStr;  
}  
  
//+---------------------------------------------------  
//| 取得当前日期所在月的最大天数  
//+---------------------------------------------------  
Date.prototype.MaxDayOfDate = function()  
{   
    var myDate = this;  
    var ary = myDate.toArray();  
    var date1 = (new Date(ary[0],ary[1]+1,1));  
    var date2 = date1.dateAdd(1,\'m\',1);  
    var result = dateDiff(date1.Format(\'yyyy-MM-dd\'),date2.Format(\'yyyy-MM-dd\'));  
    return result;  
}  
  
//+---------------------------------------------------  
//| 取得当前日期所在周是一年中的第几周  
//+---------------------------------------------------  
Date.prototype.WeekNumOfYear = function()  
{   
    var myDate = this;  
    var ary = myDate.toArray();  
    var year = ary[0];  
    var month = ary[1]+1;  
    var day = ary[2];  
    document.write(\'< script language=VBScript\> \n\');  
    document.write(\'myDate = Datue(\'\'+month+\'-\'+day+\'-\'+year+\'\') \n\');  
    document.write(\'result = DatePart(\'ww\', myDate) \n\');  
    document.write(\' \n\');  
    return result;  
}  
  
//+---------------------------------------------------  
//| 字符串转成日期类型   
//| 格式 MM/dd/YYYY MM-dd-YYYY YYYY/MM/dd YYYY-MM-dd  
//+---------------------------------------------------  
function StringToDate(DateStr)  
{   
  
    var converted = Date.parse(DateStr);  
    var myDate = new Date(converted);  
    if (isNaN(myDate))  
    {   
        //var delimCahar = DateStr.indexOf(\'/\')!=-1?\'/\':\'-\';  
        var arys= DateStr.split(\'-\');  
        myDate = new Date(arys[0],--arys[1],arys[2]);  
    }  
    return myDate;  
}  

 如果要实现这样的时钟：

2012年12月03日 17:21:16 星期一

//本地时钟
function clockon() {
    var now = new Date();
    var year = now.getFullYear(); //getFullYear getYear
    var month = now.getMonth();
    var date = now.getDate();
    var day = now.getDay();
    var hour = now.getHours();
    var minu = now.getMinutes();
    var sec = now.getSeconds();
    var week;
    month = month + 1;
    if (month < 10) month = "0" + month;
    if (date < 10) date = "0" + date;
    if (hour < 10) hour = "0" + hour;
    if (minu < 10) minu = "0" + minu;
    if (sec < 10) sec = "0" + sec;
    var arr_week = new Array("星期日", "星期一", "星期二", "星期三", "星期四", "星期五", "星期六");
    week = arr_week[day];
    var time = "";
    time = year + "年" + month + "月" + date + "日" + " " + hour + ":" + minu + ":" + sec + " " + week;

    $("#bgclock").html(time);

    var timer = setTimeout("clockon()", 200);
}