//获取滚动条滚动距离
function getScrollTop(){

        var    fromTop=document.documentElement.scrollTop||document.body.scrollTop||window.pageYOffset;

        return fromTop;

    }
//修改滚动条滚动距离

function changeScroll(num){

        if(document.documentElement.scrollTop){

            document.documentElement.scrollTop+=num;

        }

        else if(document.body.scrollTop){

            document.body.scrollTop+=num;

        }

        else{

            window.pageYOffset+=num;

        }

    }

function countDown(time){      ///time为倒计时的秒

                var timer;

                var hours,minutes,seconds;

                timer=setInterval(function(){

                    if(time==){

                        clearInterval(timer);

                    }

                    console.log();

                    hours=parseInt((time/)/);

                    minutes=parseInt((time/)%);

                    seconds=parseInt(time%);

                    hours=hours>?hours:""+hours;

                    minutes=minutes>?minutes:""+minutes;

                    seconds=seconds>?seconds:""+seconds;

                    document.getElementById("countdown").innerHTML=hours+":"+minutes+":"+seconds;

                    time--;

                },);

            }