Calculating Time Difference in Javascript

Question

I am trying to find time differences. Difference is NaN. What should I do?

currentTime.format() = 2016-12-07T11:43:19+03:00
pws.lastDataTime = 2016-12-07T08:35:14.4126931+00:00

var difference= currentTime.format() - pws.lastDataTime;

`currentTime.format()` - what type of object is this? - `pws.lastDataTime` and this ... do both return a `Date` object? or at least a `Number` that is at least somehow related to dates? — Jaromanda X, Dec 07 '16 at 08:42
Possible duplicate of [Check time difference in Javascript](http://stackoverflow.com/questions/1787939/check-time-difference-in-javascript) — Vucko, Dec 07 '16 at 08:42

score 0 · Answer 1 · answered Dec 07 '16 at 08:50

currentTime.format() = 2016-12-07T11:43:19+03:00

currentTime.format is a function. You can't assign it's return value to something.

currentTime.format() - pws.lastDataTime

I don't think the format function returns a number, but instead a string or an object. If you subtract anything from them, they return NaN (not a number). You need to either convert both to milliseconds and subtract one from the other, or calculate the year, month, day, hour, second and millisecond separately.

score 0 · Answer 2 · answered Dec 07 '16 at 08:59

I don't know what denomination you want, so I'll just show you how to find it in milliseconds.

If already you have a date or two, you can use date.getTime().

var stackOverflowLaunchDate = new Date(2008, 8, 15);
var today = new Date();
var diff = today.getTime() - stackOverflowLaunchDate.getTime(); // milliseconds since Stack Overflow was launched

If you don't have (and don't need) a date object, use Date.now() to get millisecondds since epoch

var start = Date.now();

// ... Some time later
var diff = Date.now() - start; // milliseconds since start

Calculating Time Difference in Javascript

2 Answers2