[javascript] How Many Seconds Between Two Dates?

So I have two dates YYYY-MM-DD and ZZZZ-NN-EE

How can I find out how many seconds there are between them?

var a = new Date("2010 jan 10"),
    b = new Date("2010 jan 9");

alert(
    a + "\n" + 
    b + "\n" +
    "Difference: " + ((+a - +b) / 1000)
);

Easy Way:

function diff_hours(dt2, dt1) 
 {

  var diff =(dt2.getTime() - dt1.getTime()) / 1000;
  diff /= (60 * 60);
  return Math.abs(Math.round(diff));

 }


function diff_minutes(dt2, dt1) 
 {

  var diff =(dt2.getTime() - dt1.getTime()) / 1000;
  diff /= (60);
  return Math.abs(Math.round(diff));

 }

function diff_seconds(dt2, dt1) 
 {

  var diff =(dt2.getTime() - dt1.getTime()) / 1000;
  return Math.abs(Math.round(diff));

 }

function diff_miliseconds(dt2, dt1) 
 {

  var diff =(dt2.getTime() - dt1.getTime());
  return Math.abs(Math.round(diff));

 }


dt1 = new Date(2014,10,2);
dt2 = new Date(2014,10,3);
console.log(diff_hours(dt1, dt2));


dt1 = new Date("October 13, 2014 08:11:00");
dt2 = new Date("October 14, 2014 11:13:00");
console.log(diff_hours(dt1, dt2));

console.log(diff_minutes(dt1, dt2));

console.log(diff_seconds(dt1, dt2));

console.log(diff_miliseconds(dt1, dt2));

In bash:

bc <<< "$(date --date='1 week ago' +%s) - \
    $(date --date='Sun,  29 Feb 2004 16:21:42 -0800' +%s)"

It does require having bc and gnu date installed.

create two Date objects and call valueOf() on both, then compare them.

JavaScript Date Object Reference

If one or both of your dates are in the future, then I'm afraid you're SOL if you want to-the-second accuracy. UTC time has leap seconds that aren't known until about 6 months before they happen, so any dates further out than that can be inaccurate by some number of seconds (and in practice, since people don't update their machines that often, you may find that any time in the future is off by some number of seconds).

This gives a good explanation of the theory of designing date/time libraries and why this is so: http://www.boost.org/doc/libs/1_41_0/doc/html/date_time/details.html#date_time.tradeoffs

You can do it simply.

var secondBetweenTwoDate = Math.abs((new Date().getTime() - oldDate.getTime()) / 1000);

Just subtract:

var a = new Date();
alert("Wait a few seconds, then click OK");

var b = new Date();
var difference = (b - a) / 1000;

alert("You waited: " + difference + " seconds");

.Net provides the TimeSpan class to do the math for you.

var time1 = new Date(YYYY, MM, DD, 0, 0, 0, 0)
var time2 = new Date(ZZZZ, NN, EE, 0, 0, 0, 0)

Dim ts As TimeSpan = time2.Subtract(time1)

ts.TotalSeconds