Momentjs and countdown timer

Question

I found the Momentjs library which is pretty cool, however I don't find the documentation to be very clear on how to achieve some simple tasks. I'm trying to build a countdown timer and I'm guessing I should use the duration object, but I don't quite understand how (maybe due to the fact that English isn't my first language). Anyways this is what I want:

var time = 7200;
var duration = moment.duration('seconds',time);

setInterval(function(){
  //show how many hours, minutes and secods are left
  $('.countdown').text(duration.format('h:mm:ss')); 
  //this doesn't work because there's no method format for the duration object.
},1000);

So everysecond it should display:

02:00:00

01:59:59

01:59:58

01:59:57

...

00:00:00

How would I achieve this result with the Momentjs library? Thanks!

Answer 1

duration object represents a static period, and it does not increase/decrease with the flow of time. So if you what to decrease it you have to do it yourself, for example creating a kind of a seconds counter or recreating duration object every time. Here is the code for the second option:

var time = 7200;
var duration = moment.duration(time * 1000, 'milliseconds');
var interval = 1000;

setInterval(function(){
  duration = moment.duration(duration.asMilliseconds() - interval, 'milliseconds');
  //show how many hours, minutes and seconds are left
  $('.countdown').text(moment(duration.asMilliseconds()).format('h:mm:ss'));
}, interval);

Answer 2

I don't know Momentjs very well either, but I think you are looking for something like this:

var time = 7200;
var duration = moment.duration('seconds',time);

setInterval(function(){
    var countdown = duration.milliseconds();
    $('.countdown').text(moment(countdown).format('h:mm:ss')); 
},1000);