Invalid dates are parsed as valid

[manojkakarla]

Invalid dates are parsed resulting in incorrect values
e.g,
const dt = dayjs('1993-51-11')
dt.isValid() returns true and dt.format('YYYY-MM-DD') returns 1997-03-11
const dt = dayjs('1993-51-41')
dt.isValid() returns true and dt.format('YYYY-MM-DD') returns 1997-04-10
infact dayjs('1993-08-21', 'YYYY/MM/DD') returns true for isValid()

isValid() should return false for all these

Information

• Day.js Version: v1.9.6
• OS: macOS 11 BigSur
• Browser: chrome 86
• Time zone: GMT

[iamkun]

Yes, this is valid to js Date.

You can use strict parsing to get what you need. https://day.js.org/docs/en/parse/string-format

dayjs('1970-00-00', 'YYYY-MM-DD', true).isValid() // false 

[bornova]

Does Day.js strict parsing validate time formats as well? Following returns true. Should it return false since date string is missing the time?

dayjs('12/3/2020', 'M/D/YYYY h:mm A', true).isValid() // true

[iamkun]

well, seems this is something we've never think about it.

this depends on how we define 'isValid', it should be a valid date-time？ or valid and match the given format？

[bornova]

IMHO, it should match the given format. Btw, I also found the following:

dayjs('1/30/2020', 'M/D/YYYY', true).isValid() // true
but
dayjs('30/1/2020 10:59 PM', 'D/M/YYYY h:mm A', true).isValid() // false

Both should be true.

[Gabee01]

+1

[Gabee01]

using the strict boolean does not work here as well. dayjs('00-00-1990', 'DD-MM-YYYY', true).isValid() // true
edit: As @bornova script shows, it really works. Maybe my mistake were somewhere else

[bornova]

using the strict boolean does not work here as well.
dayjs('00-00-1990', 'DD-MM-YYYY', true).isValid() // true

@Gabee01 Your example returns the correct value (false) on my end: https://runkit.com/5fd149b2b4b41f001d9b4bf4/5fd149f5b4b41f001d9b4c26

[Gabee01]

@bornova I'm now wondering what have I done wrong at the time. I tested the validation several times, before giving up on this. It really looks like its working on runkit..

[iamkun]

Do remember this dependent on CustomParseFormat plugin to work https://day.js.org/docs/en/parse/string-format

[Gabee01]

@iamkun CustomParseFormat was really missing. thanks!

[bornova]

@iamkun My issue still remains:
https://runkit.com/5fd79efc6abad7001a703bb0/5fd79f0342c42e001ad68c00

Any plans to address this in the near future? I had to switch back to Moment.js for the time being. Thanks for all your effort in this library!

[iamkun]

@bornova fixed in #1321

[iamkun]

🎉 This issue has been resolved in version 1.10.3 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀

[ghiscoding]

@iamkun I think you should reopen

This doesn't seem to be fixed, I want to migrate my lib from MomentJS to DayJS, so I'm fairly new to it but this is a bit of blocker to migrate. I expect the following lines to be both invalid and not be parseable/formattable

// with version 1.10.4
console.log(dayjs('1900-02-33', 'YYYY-MM-DD', true).isValid())  // true but should be false 33 is not a valid date
console.log(dayjs('1900-02-33', 'MM/DD/YYYY', true).isValid())  // true but again should be false 33 is not valid and it also shouldn't be parseable 

// trying to format them also works but changes the date completely
console.log(dayjs('1900-02-33', 'YYYY-MM-DD', true).format('MM/DD/YYYY'))  // "03/05/1900"
console.log(dayjs('1900-02-33', 'MM/DD/YYYY', true).format('MM/DD/YYYY'))  // "03/05/1900"

If I take the same code and use MomentJS it's throwing "Invalid date" (even without using strict) and I rely on that error message

EDIT

I read the CustomParseFormat after and now yes now it works. So you can forget my comment, thanks

[rrdlpl]

This should be reopened it's still happening for me

var dayjs = require("dayjs")
require('dayjs/locale/en')



var datestr= '20201312'

console.log(dayjs(datestr, 'YYYYMMDD', 'en', true).isValid()); // Returns true. 13 is not a valid month.

https://runkit.com/embed/1bnw0lmx5yv2

[ghiscoding]

@rrdlpl I think you did the same mistake as I did which is to forget adding CustomParseFormat for validating dates

[rrdlpl]

@ghiscoding I don;t understand what you meant. Could you please update my fiddle?

[ghiscoding]

@rrdlpl read this comment

[rrdlpl]

For the people that still are struggling with this. As the other people mentioned you need CustomParseFormat

const dayjs = require("dayjs")
require('dayjs/locale/en')
const customParseFormat = require('dayjs/plugin/customParseFormat');
dayjs.extend(customParseFormat);

const datestr= '20201312'

console.log(dayjs(datestr, 'YYYYMMDD', 'en', true).isValid()); 

[wmonecke]

Why is this issue closed? I don't understand. I guess I am going back to moment.

[glendell03]

I was filtering my db and when I filter slug text "cajina-06-08-2021" it says true

[NikhilNanjappa]

Extending customParseFormat does not fix this for me

I still get incorrect results (v1.11.3)

const customParseFormat = require('dayjs/plugin/customParseFormat')
dayjs.extend(customParseFormat)

dayjs('2001-2-29', 'YYYY-M-D', true).isValid() // returns true; expected false

[sensetive5]

@NikhilNanjappa

Works correctly

https://codesandbox.io/s/dayjs-playground-forked-d24ksp?file=/src/index.js