Why new Date(null) is returning this: Date 1970-01-01T00:00:00.000Z?

Question

new Date(null)
// Date 1970-01-01T00:00:00.000Z

How come when I type new Date(null) in JavaScript console I'm getting
Date 1970-01-01T00:00:00.000Z?

[Unix epoch](https://en.wikipedia.org/wiki/Unix_time) – ASDFGerte Mar 17 '18 at 17:46 — ASDFGerte, Mar 17 '18 at 17:46

Paul T. · Answer 1 · 2018-08-24T00:54:11.510

Because the ECMAScript 2017 standard says so?

The end of ECMA section 20.3.1.1 claims:

The exact moment of midnight at the beginning of 01 January, 1970 UTC is represented by the value +0.

...which might make you say, "...but!, but!, I did not say +0, I said":

new Date(null)

Ok, so let's follow the standard on that one...

That Date constructor example goes to section 20.3.2.2, where item 3.b.iii there says:

3.b.iii: Else, let V be ToNumber(v).

ToNumber is a hyperlink, so follow that to section 7.1.3 where there is a number conversion table that shows:

Argument Type | Result
Null | +0

Therefore:

new Date(null)

Effectively becomes:

new Date(+0)

Which is why you ultimately get:

Date 1970-01-01T00:00:00.000Z

@Beki ... you could do something like: `new Date(Date.now())` or pass some other date value that can be used. — Paul T., Apr 18 '22 at 00:41

score 2 · Answer 2 · answered Mar 17 '18 at 17:57

2

Apparently because that (Unix timestamp 0) is what a Date object is initialized to by default, eh?

answered Mar 17 '18 at 17:57

bipll

score 0 · Answer 3 · answered Apr 30 '20 at 15:19

0

On doing new Date(null), it returns Wed Dec 31 1969 19:00:00 GMT-0500 (Eastern Standard Time) for me.

answered Apr 30 '20 at 15:19

Siddharth Jain

1

This is 1/1/1970 at midnight in UTC time, which is the Unix epoch. This means your result is the same as in the question, accounting for timezone differences. – Oliver Nov 11 '20 at 22:38

3 Answers3