var d = new Date();
var year = d.getFullYear()+1;
var countDownDate = new Date(+year+" 00:00:00").getTime();
var x = setInterval(function() {
var now = new Date().getTime();
var distance = countDownDate - now;
var days = Math.floor(distance / (1000 * 60 * 60 * 24));
var hours = Math.floor((distance % (1000 * 60 * 60 * 24)) / (1000 * 60 * 60));
var minutes = Math.floor((distance % (1000 * 60 * 60)) / (1000 * 60));
var seconds = Math.floor((distance % (1000 * 60)) / 1000);
if(hours < 10) {
hours = '0'+hours;
}
if(minutes < 10) {
minutes = '0'+minutes;
}
if(seconds < 10) {
seconds = '0'+seconds;
}
document.getElementById("countdown").innerHTML = ' Còn ' + days + ' Ngày ' + hours + ' : '
+ minutes + ' : ' + seconds;