倒计时（图片倒计时）

countDown: function(){
    var timer = null,
        nextH = 0, //初始小时
        nextM = 0, //初始分钟
        nextS = 3, //初始秒
        hPrev = hAfter = mPrev = mAfter = sPrev = sAfter = 0;

    var hour = splitUnitDecade(nextH);
    var minute = splitUnitDecade(nextM);
    var second = splitUnitDecade(nextS);

    $(".hour-prev")[0].src = commonImgUrl + "0"+hour[0]+".png";
    $(".hour-after")[0].src = commonImgUrl + "0"+hour[1]+".png";
    $(".minute-prev")[0].src = commonImgUrl + "0"+minute[0]+".png";
    $(".minute-after")[0].src = commonImgUrl + "0"+minute[1]+".png";
    $(".second-prev")[0].src = commonImgUrl + "0"+second[0]+".png";
    $(".second-after")[0].src = commonImgUrl + "0"+second[1]+".png";

    //个位和十位
    function splitUnitDecade(num){ 
        var numArr = [];
            unitNum = num % 10,
            decateNum = parseInt(num / 10);

        numArr.push(decateNum);
        numArr.push(unitNum);

        return numArr;
    }

    if(nextH==0 && nextM==0 && nextS==0){
        clearInterval(timer);
    }else{
        timer = setInterval(function(){
            if(nextS == 0){
                if(nextM == 0){
                    if(nextH == 0){
                        clearInterval(timer);
                    }else{
                        nextH--;
                        var hour = splitUnitDecade(nextH);

                        $(".hour-prev")[0].src = commonImgUrl + "0"+hour[0]+".png";
                        $(".hour-after")[0].src = commonImgUrl + "0"+hour[1]+".png";

                        nextM = 59;
                        $(".minute-prev")[0].src = commonImgUrl + "05.png";
                        $(".minute-afterr")[0].src = commonImgUrl + "09.png";
                    }
                }else{
                    nextM--;
                    var minute = splitUnitDecade(nextM);

                    $(".minute-prev")[0].src = commonImgUrl + "0"+minute[0]+".png";
                    $(".minute-after")[0].src = commonImgUrl + "0"+minute[1]+".png";

                    nextS = 59;
                    $(".second-prev")[0].src = commonImgUrl + "05.png";
                    $(".second-after")[0].src = commonImgUrl + "09.png";
                }
            }else{
                nextS--;
                var second = splitUnitDecade(nextS);

                $(".second-prev")[0].src = commonImgUrl + "0"+second[0]+".png";
                $(".second-after")[0].src = commonImgUrl + "0"+second[1]+".png";
            }
        },1000)
    }
}