Ну, собственно, вот так:
<div id="timer">
<div id="tm1" data="02/19/2016 10:1"></div>
<div id="tm2" data="02/14/2016 20:1"></div>
<div id="tm3" data="02/12/2016 01:1"></div>
</div>
var elems = document.getElementById('timer').childNodes,
id_tm = '',
tm = '';
[].forEach.call(elems, function(elem) {
if( elem.tagName == 'DIV'){
id_tm = elem.getAttribute('id');
tm = elem.getAttribute('data');
CountDownTimer(tm, id_tm);
}
});
function CountDownTimer(dt, id)
{
var end = new Date(dt);
var _second = 1000;
var _minute = _second * 60;
var _hour = _minute * 60;
var _day = _hour * 24;
var timer;
function showRemaining() {
var now = new Date();
var distance = end - now;
if (distance < 0) {
clearInterval(timer);
document.getElementById(id).innerHTML = 'EXPIRED!';
return;
}
var days = Math.floor(distance / _day);
var hours = Math.floor((distance % _day) / _hour);
var minutes = Math.floor((distance % _hour) / _minute);
var seconds = Math.floor((distance % _minute) / _second);
document.getElementById(id).innerHTML = days + 'days ';
document.getElementById(id).innerHTML += hours + 'hrs ';
document.getElementById(id).innerHTML += minutes + 'mins ';
document.getElementById(id).innerHTML += seconds + 'secs';
}
timer = setInterval(showRemaining, 1000);
}