convert-seconds-to-date-object.md

Convert Seconds To Date Object

Let's say you have an integer that represents the number of seconds since the unix epoch. This is a reasonably common way for systems to represent a date.

For example, 1713350171 is an Expiration Date I just got from an API.

But how do we know what date that actually represents and how can we get a JavaScript Date object from that value?

The new Date() constructor can produce a date object given an integer. That integer is not supposed to be seconds since the unix epoch though. See what we get here:

> new Date(1713350171)
1970-01-20T19:55:50.171Z

Something is off. The integer that you pass to new Date() needs to be the number of milliseconds since the unix epoch. We can get there by multiplying our seconds value by 1000.

> new Date(1713350171 * 1000)
2024-04-17T10:36:11.000Z

Not only can we, as humans, read that date, but we have a Date object that we can use within our program.

Note: if you execute Date.now(), the value you get is in milliseconds.