js倒计时 总结

 1 var countDown = function (){
 2     var date1 = new Date("2015/4/9"); //目标日期 注意字符串 /格式 -格式IE不支持
 3     var date2 = new Date();//当前日期
 4     
 5     var times = date1.getTime() - date2.getTime();//相差毫秒数
 6     
 7     var days = Math.floor(times/(1000*60*60*24)) ///剩余天数
 8     var rest1 = times%(1000*60*60*24); //取余数
 9     
10     var hours = Math.floor(rest1/(1000*60*60));
11     var rest2 = rest1%(1000*60*60);
12     
13     var minutes = Math.floor(rest2/(1000*60));
14     var rest3 = rest2%(1000*60);
15     
16     var seconds = Math.round(rest3/(1000));///最后秒数四舍五入就可以了
17     
18     var zero = function (num){
19         return num < 10 ? "0" + num : num;
20     };
21     
22     document.body.innerHTML = 
23             ‘倒计时：‘
24             + days + "天 "
25             + zero(hours) + "时 "
26             + zero(minutes) + "分 "
27             + zero(seconds) + "秒 ";
28     
29 }
30 countDown();
31 setInterval(countDown,1000);