Try
// set the date we're counting down to
var target_date_opening = new Date("Jul 23, 2014").getTime();
var target_date_closing = new Date("Aug 23, 2014").getTime();
// variables for time units
var days, hours, minutes, seconds;
// get tag element
var countdownOpening = document.getElementById("countdownOpening");
var countdownClosing = document.getElementById("countdownClosing");
// update the tag with id "countdownOpening" every 1 second
setInterval(function () {
print(countdownOpening, target_date_opening)
print(countdownClosing, target_date_closing)
}, 1000);
function print(el, time) {
// find the amount of "seconds" between now and target
var current_date = new Date().getTime();
var seconds_left = (time - current_date) / 1000;
// do some time calculations
var days = parseInt(seconds_left / 86400);
seconds_left = seconds_left % 86400;
var hours = parseInt(seconds_left / 3600);
seconds_left = seconds_left % 3600;
var minutes = parseInt(seconds_left / 60);
var seconds = parseInt(seconds_left % 60);
// format countdown string + set tag value
el.innerHTML = days + " days " + hours + " hours " + minutes + " minutes " + seconds + " seconds";
}
Demo: Fiddle