时分秒倒计时的js实现

<div id="timer" data-timer="20160628140203" style="font-size:20px">  
    剩余天数：  
    <span id="timer_d">0</span>天  
    <span id="timer_h">0</span>时  
    <span id="timer_m">0</span>分  
    <span id="timer_s">0</span>秒  
</div> 

timer(‘timer‘);//调用方法  
          
//时分秒倒计时方法  
function timer(eleId){  
    var element=document.getElementById(eleId);  
    if(element){  
        endTimer=element.getAttribute(‘data-timer‘);  
        var endTime=new Date(parseInt(endTimer.substr(0,4), 10),parseInt(endTimer.substr(4,2), 10),parseInt(endTimer.substr(6,2), 10),parseInt(endTimer.substr(8,2), 10),parseInt(endTimer.substr(10,2), 10),parseInt(endTimer.substr(12,2), 10));  
        var endTimeMonth=endTime.getMonth()-1;  
        endTime.setMonth(endTimeMonth);  
        var ts = endTime - new Date();  
        if(ts>0){  
            var dd = parseInt(ts / 1000 / 60 / 60 / 24, 10);  
            var hh = parseInt(ts / 1000 / 60 / 60 % 24, 10);  
            var mm = parseInt(ts / 1000 / 60 % 60, 10);  
            var ss = parseInt(ts / 1000 % 60, 10);  
            dd = dd<10?("0" + dd):dd;   //天  
            hh = hh<10?("0" + hh):hh;   //时  
            mm = mm<10?("0" + mm):mm;   //分  
            ss = ss<10?("0" + ss):ss;   //秒  
            document.getElementById("timer_d").innerHTML=dd;  
            document.getElementById("timer_h").innerHTML=hh;  
            document.getElementById("timer_m").innerHTML=mm;  
            document.getElementById("timer_s").innerHTML=ss;  
            setTimeout(function(){timer(eleId);},1000);  
        }else{  
            document.getElementById("timer_d").innerHTML=0;  
            document.getElementById("timer_h").innerHTML=0;  
            document.getElementById("timer_m").innerHTML=0;  
            document.getElementById("timer_s").innerHTML=0;  
        }  
    }  
}