Unix Time

Wiki

Unix Time, POSIX time, UNIX Epoch Time all mean the same thing. Describes a point in time defined as a number of seconds that have elapsed since 00:00:00 UTC Thursday, 1 January 1970.

UTC +1 hour ⇒ CET
UTC +2 hours ⇒ CEST

Javascript

MDN web docs - Date

JavaScript Date objects are based on a time value that is the number of milliseconds since 00:00:00 UTC Thursday, 1 January 1970. They can only be instantiated by calling the Date constructor and use the system's locale.

Getting Current Unix Epoch Time

Math.floor(Date.now() / 1000);

Setting a Specific Time on the Current Day

const date = new Date();
date.setHours(17, 15, 0);

Calculating the Difference in Seconds Between Two Dates

const date = new Date();
date.setHours(date.getHours() + 1);
const now = Date.now();
Math.floor((date.getTime() - now) / 1000);
// outputs 3600

PHP

PHP Manual - Date and Time

In PHP, you can manipulate Unix Time using the time() function and the DateTime class.

Getting Current Unix Epoch Time_

// Current Unix Epoch Time in seconds
$currentUnixTimeSeconds = time();

// Current Unix Epoch Time in milliseconds
$currentUnixTimeMilliseconds = round(microtime(true) * 1000);

Calculating the Difference in Seconds Between Two Dates_

$dateTime1 = new DateTime();
$dateTime2 = clone $dateTime1;
$dateTime2->modify('+1 hour');

$unixTime1 = $dateTime1->getTimestamp();
$unixTime2 = $dateTime2->getTimestamp();

$differenceInSeconds = $unixTime2 - $unixTime1;

C#

Microsoft Docs - DateTime

In C#, you can work with Unix Time using the DateTime class. Unix Time is represented as the number of seconds or milliseconds since January 1, 1970.

Getting Current Unix Epoch Time*

// Current Unix Epoch Time in seconds
long unixTimeSeconds = (long)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalSeconds;

// Current Unix Epoch Time in milliseconds
long unixTimeMilliseconds = (long)(DateTime.UtcNow - new DateTime(1970, 1, 1)).TotalMilliseconds;

Calculating the Difference in Seconds Between Two Dates*

DateTime dateTime1 = DateTime.UtcNow;
DateTime dateTime2 = dateTime1.AddHours(1);

long unixTime1 = dateTime1.ToUnixTimeSeconds();
long unixTime2 = dateTime2.ToUnixTimeSeconds();

long differenceInSeconds = unixTime2 - unixTime1;