Calculate the difference in seconds between two epoch timestamps in Javascript

Question

I'm trying to calculate the difference (in seconds) between two EPOCH timestamps using Javascript.

I have two timestamps:

START: 1565628094441
END: 1565714527812

Both timestamps were obtained using:

var time = new Date().getTime().toString();

I would like to determine the difference between both timestamps in seconds. I understand that Javascript returns epoch in milliseconds but I still haven't been able to find a way to convert them to seconds properly.

Here is what I've tried:

var differenceSec = (END- START)/1000;
// This gives us 86433.371 Seconds (~1440 minutes). 

Using Epoch Converter (https://www.epochconverter.com/#tools) I know that the true difference should be around 30 seconds. What am I doing wrong here?

Solution

There are 24 * 60 * 60 = 86400 seconds in a day. Your figure of 86433.371 - 1 day = 33.371 seconds. So if Epoch Converter is not counting days, you have your answer