moment js bug : unexpected behavior when I select new timezone - momentjs

Question

Unexpected behavior I first select the timezone in drop-down when I press another timezone in select, the previous selected timezone are save.
function run(){
var timeZone = document.getElementById("selectTimezone");
var i = timeZone.selectedIndex;
var removeParenthesis = timeZone.options[i].text.replace(/[()]/g, '')
var splitString = removeParenthesis.split(' ')
var d = new Date('Nov 1, 2017 ' + ' ' + splitString[0])
var $clock = $('#clock'),
eventTime = moment(d.getTime()).unix(),
currentTime = moment(new Date().getTime()).unix(),
diffTime = eventTime - currentTime,
duration = moment.duration(diffTime * 1000, 'milliseconds'),
interval = 1000;
// if time to countdown
if(diffTime > 0) {
// Show clock
// $clock.show();
setInterval(function(){
duration = moment.duration(duration.asMilliseconds() - interval, 'milliseconds');
var d = moment.duration(duration).days(),
h = moment.duration(duration).hours(),
m = moment.duration(duration).minutes(),
s = moment.duration(duration).seconds();
d = $.trim(d).length === 1 ? '0' + d : d;
h = $.trim(h).length === 1 ? '0' + h : h;
m = $.trim(m).length === 1 ? '0' + m : m;
s = $.trim(s).length === 1 ? '0' + s : s;
// show how many hours, minutes and seconds are left
$('.days').text(d + 'days');
$('.hours').text(h + 'hours');
$('.minutes').text(m + 'minutes');
$('.seconds').text(s + 'seconds');
}, interval);
}
}
https://codepen.io/edward1995/pen/oGpMOq

Answer 1

Clear the interval before starting a new one
var myInterval;// Used to save previous interval if one has been started
function run(){
var timeZone = document.getElementById("selectTimezone");
var i = timeZone.selectedIndex;
var removeParenthesis = timeZone.options[i].text.replace(/[()]/g, '')
var splitString = removeParenthesis.split(' ')
var d = new Date('Nov 1, 2017 ' + ' ' + splitString[0])
var $clock = $('#clock'),
eventTime = moment(d.getTime()).unix(),
currentTime = moment(new Date().getTime()).unix(),
diffTime = eventTime - currentTime,
duration = moment.duration(diffTime * 1000, 'milliseconds'),
interval = 1000;
// if time to countdown
if(diffTime > 0) {
// Show clock
// $clock.show();
clearInterval(myInterval);
myInterval = setInterval(function(){
duration = moment.duration(duration.asMilliseconds() - interval, 'milliseconds');
var d = moment.duration(duration).days(),
h = moment.duration(duration).hours(),
m = moment.duration(duration).minutes(),
s = moment.duration(duration).seconds();
d = $.trim(d).length === 1 ? '0' + d : d;
h = $.trim(h).length === 1 ? '0' + h : h;
m = $.trim(m).length === 1 ? '0' + m : m;
s = $.trim(s).length === 1 ? '0' + s : s;
// show how many hours, minutes and seconds are left
$('.days').text(d + 'days');
$('.hours').text(h + 'hours');
$('.minutes').text(m + 'minutes');
$('.seconds').text(s + 'seconds');
}, interval);
}
}