new Date(milliseconds) returns Invalid date

Question

I am trying to convert milliseconds to a date using the javascript using:

new Date(Milliseconds);

constructor, but when I give it a milliseconds value of say 1372439683000 it returns invalid date. If I go to a site that converts milliseconds to date it returns the correct date.

Any ideas why?

`alert(new Date(1372439683000));` works for me. What do you mean by "invalid date" exactly, what result are you getting? — Pekka, Jun 28 '13 at 18:27
@Pekka웃 The OP is getting a `Date` object that stringifies to "`Invalid Date`". (e.g., try out `alert(new Date(""))`) — apsillers, Jun 28 '13 at 18:40

apsillers · Accepted Answer · 2013-06-28T18:37:57.300

111

You're not using a number, you're using a string that looks like a number. According to MDN, when you pass a string into Date, it expects

a format recognized by the parse method (IETF-compliant RFC 2822 timestamps).

An example of such a string is "December 17, 1995 03:24:00", but you're passing in a string that looks like "1372439683000", which is not able to be parsed.

Convert Milliseconds to a number using parseInt, or a unary +:

new Date(+Milliseconds); 
new Date(parseInt(Milliseconds,10));

edited Jun 28 '13 at 18:37

answered Jun 28 '13 at 18:30

apsillers

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`new Date(929397621000)` in Developer Tools returns a validly formatted date string `Mon Jun 14 1999 15:00:21 GMT-0700 (PDT)` yet when I try to inspect the object, it shows "Invalid Date". And in the actual code where this is being used, it also creates an invalid date. – Michael Apr 01 '15 at 17:17
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@Michael This appears to be a different issue from the one described here. Are you doing `console.dir(new Date(929397621000))`? If so, seeing `__proto__: Invalid Date` inside that instance is correct (or at least unsurprising) behavior. The `Date` *prototype* *is* an invalid date; valid date information exists on `Date` *instances*, not on the prototype. – apsillers Apr 01 '15 at 17:21
I'm entering the expression directly as a watch in Chrome's developer tools. My code is basically doing the same thing. Since I'm calling `new` that should produce a valid Date object, yes? Strangely, even `new Date()` is producing an invalid date (that the debugger can strangely stringify correctly) which I cannot inspect the elements of (because it only shows "Invalid Date") so maybe it is a cockpit issue. – Michael Apr 01 '15 at 17:23
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Well, it appears that the problem only occurs in the inspector... the actual object is valid, even though inspecting the object shows it is invalid. – Michael Apr 01 '15 at 17:26
@Michael Your issues appears to be nuanced enough to merit a new question post (or bug report?) – apsillers Apr 01 '15 at 17:26
nah, it turned out the problem was a string being passed in (for some reason, the variable was supposed to be a number, but why it isn't is for a separate debug session) but then after i fixed it i was trying to verify it in the debugger, and ran across this Chrome issue/quirk - doesn't really cause any harm, just made me think the bug wasn't fixed. – Michael Apr 01 '15 at 17:37
In my case I was fetching the data and it came as 1.495462321562E12. It was a string and hence I tried to convert it to int and it failed. The actual thing to do there was parseFloat(). – SKT May 22 '17 at 14:22

score 5 · Answer 2 · answered Jun 28 '13 at 18:29

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The Date function is case-sensitive:

new Date(Milliseconds);

answered Jun 28 '13 at 18:29

ic3b3rg

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score 1 · Answer 3 · answered Jun 28 '13 at 18:29

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instead of this

new date(Milliseconds);

use this

new Date(Milliseconds);

your statement will give you date is not defined error

answered Jun 28 '13 at 18:29

Sachin

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score 1 · Answer 4 · answered Sep 16 '21 at 11:46

Is important to note that the timestamp parameter MUST be a number, it cannot be a string.

new Date(1631793000000).toLocaleString('en-GB', { timeZone: 'America/Argentina/Buenos_Aires' });

// Returns: '16/09/2021, 08:50:00'

new Date("1631793000000").toLocaleString('en-GB', { timeZone: 'America/Argentina/Buenos_Aires' });

// Returns: 'Invalid Date'

In case you're receiving the timestamp as string, you can simply wrap it around parseInt(): parseInt(your_ts_string)

score 0 · Answer 5 · answered Sep 21 '15 at 08:23

I was getting this error due to a different reason.

I read a key from redis whose value is a json.

client.get(someid, function(error, somevalue){});

Now i was trying to access the fields inside somevalue (which is a string), like somevalue.start_time, without parsing to JSON object. This was returning "undefined" which if passed to Date constructor, new Date(somevalue.start_time) returns "Invalid date".

So first using JSON.parse(somevalue) to get JSON object before accessing fields inside the json solved the problem.

new Date(milliseconds) returns Invalid date

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