/**
     * 获取当前时间
     * format=1精确到天
     * format=2精确到分
    */
    function getCurrentDate(format){
        var now = new Date();
        var year = now.getFullYear();//得到年份
        var month = now.getMonth();//得到月份
        var date = now.getDate();//得到日期
        var day = now.getDay();//得到周几
        var hour = now.getHours();//得到小时
        var minu = now.getMinutes();//得到分钟
        //var sec = now.getSenconds();//得到秒
        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 time = "";
        //精确到天
        if(format==1){
            time = year + "年" + month + "月" + date + "日";
        }
        //精确到分
        else if (format==2){
            time = year + "-" + month + "-" + date+ " "+ hour + ":" + minu + ":" + sec;
            
        }
         return time;
    }
    
 setInterval(function(){
    $('#aa').text(getCurrentDate(1));
 },1000);