取当前时间，格式为,yyyy-mm-dd hh:mm:ss

function CurentTime()
    {
        var now = new Date();

        var year = now.getFullYear();       //年
        var month = now.getMonth() + 1;     //月
        var day = now.getDate();            //日

        var hh = now.getHours();            //时
        var mm = now.getMinutes();          //分
        var ss = now.getSeconds();           //秒

        var clock = year + "-";

        if(month <)
            clock += "0";

        clock += month + "-";

        if(day < 10)
            clock += "0";

        clock += day + " ";

        if(hh < 10)
            clock += "0";

        clock += hh + ":";
        if (mm < 10) clock += '0';
        clock += mm + ":"; 

        if (ss < 10) clock += '0';
        clock += ss;
        return(clock);
}

alert(CurentTime())就可以了