1345896 - Date object representation doesn't match to Google Chrome's console (toISOString vs toString)

Status: RESOLVED DUPLICATE of bug 1073533

(DevTools :: Console, defect)

Description

[Quentin Lamamy]

User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.11; rv:51.0) Gecko/20100101 Firefox/51.0
Build ID: 20170125094131

Steps to reproduce:

1) Open a scratchpad
2) paste 
var date = new Date(2017,1,1);
console.log(date);
3) look at your console

@dditional data : same issue on nightly version


Actual results:

Date 2017-01-31T23:00:00.000Z


Expected results:

Date 2017-01-01T23:00:00.000Z

Comment 1

[Quentin Lamamy]

Google Chrome output, as expected : Wed Feb 01 2017 00:00:00 GMT+0100 (CET)

Comment 2

[Tooru Fujisawa [:arai]]

"2017-01-31T23:00:00.000Z" and "Wed Feb 01 2017 00:00:00 GMT+0100 (CET)" are the same time.

the difference comes from how the console shows the date object.

new Date(2017,1,1).toString() is "Wed Feb 01 2017 00:00:00 GMT+0100 (CET)"
and
new Date(2017,1,1).toISOString() is "2017-01-31T23:00:00.000Z"

Comment 3

[Tooru Fujisawa [:arai]]

this is not about JS engine's behavior, but just an representation in devtools console.

to be clear, the expected result in comment #0 is not correct:

> Expected results:
> 
> Date 2017-01-01T23:00:00.000Z

Comment 4

[Quentin Lamamy]

Feb 01 2017 mean 2017-01-31 ? Are you serious ? I can understand thei is something like 1 or 2 days because of timezone change but 30 day...

Comment 5

[Tooru Fujisawa [:arai]]

Feb 01 2017 = 2017-02-01

and there's 1 hour difference (23:00 vs 00:00) because of GMT vs CET

just to be sure, the 2nd parameter of Date constructor is 0-origin (0 = Jan, 1 = Feb)

Comment 6

[Quentin Lamamy]

Oh well, just understand, omg, sorry for openning this useless bug. The is no consensus on the default way to dump a date object in console ?

I now understand why my calendar sucks....

Comment 7

[Tooru Fujisawa [:arai]]

(In reply to Quentin Lamamy from comment #6)
> The is no consensus on the default way to dump a date object in console ?

I've moved this bug to developer tools console component, to see if current output is better than google chrome's one.
let's wait for a response :)

Comment 8

[Quentin Lamamy]

Ok thanks

Comment 9

[Tom Tromey :tromey]

There's already a bug open requesting the use of the local timezone when displaying Date.