dayjs('2014-01-33').format('DD/MM/YYYY') doesn't return invalid date

[hamzahamidi]

Describe the bug

const day = dayjs('2014-01-33').format('DD/MM/YYYY');
console.log(lastDay); // return 02/02/2014

doesn't return invalid date

Expected behavior
Should the above expression return invalid date or is this the expected behavior?

Information

• Day.js Version: v1.11.6
• OS: Debian version 11.5
• Browser: Chrome 107.0.5304.87
• Time zone: +1

[lessfish]

I thinks it's the expected behavior

[Bykiev]

Hi, this is not a bug, if you wish strict parsing, you can pass true as third parameter.
Read more here

[willianfalbo]

Hey @Bykiev, it is definitely a bug! What is the reason for it?
It doesn't make sense allowing a date as 2014-01-33. It is an invalid date!

Other libs such as moment, handles it as expected! Look at this example:

If that is the case, we cannot rely on this lib!

[Bykiev]

@willianfalbo, if it's described in the docs it's not a bug

There is a table of diff with moment library on the linked page

Differences to moment

title	parameters	dayjs	moment
invalid date with overflow	('35/22/2010 99:88:77', 'DD-MM-YYYY HH:mm:ss')	'08-11-2011 04:29:17'	'Invalid date'
invalid date with overflow, strict	('35/22/2010 99:88:77', 'DD-MM-YYYY HH:mm:ss', true)	'Invalid Date'	'Invalid date'
'0' day or month (using default values)	('1970-00-00', 'YYYY-MM-DD')	'1970-01-01'	'Invalid date'
'0' day or month (using default values), strict	('1970-00-00', 'YYYY-MM-DD', true)	'Invalid Date'	'Invalid date'
date not matching format	('10/12/2014', 'YYYY-MM-DD')	'01-01-2014'	'12-20-2010'
date not matching format, strict	('10/12/2014', 'YYYY-MM-DD', true)	'Invalid Date'	'Invalid date'
first match vs. longest match	('2012-05-28 10:21:15', ['YYYY', 'YYYY-MM-DD', 'YYYY-MM-DD HH:mm:ss'])	'2012-01-01 00:00:00'	'2012-05-28 10:21:15'
first match vs. longest match, strict	('2012-05-28 10:21:15', ['YYYY', 'YYYY-MM-DD', 'YYYY-MM-DD HH:mm:ss'], true)	'2012-05-28 10:21:15'	'2012-05-28 10:21:15'

[willianfalbo]

Hi @Bykiev, you are right, it is in the docs though!

Well, if dayjs accepts this, there is nothing we can do. Btw, our team replaced this lib to moment as it is more reliable in this context. Thanks