Validation fails for valid input with textual months followed by period (MMM. and MMMM.)

Describe the bug In our date field, formats including MMM and MMMM cause the dayjs(value, format, strict=true).isValid() to return false for all values.

Expected behavior IsValid() should return true

Information

• Day.js Version: dayjs@^1.10.6: version “1.11.3”
• OS: Windows 10
• Browser: Chrome
• Time zone: GMT+2 - Central European Summer Time

[BePo65]

I’ve made some tests and the issue could be easily fixed by adding a dot to the regex of matchWord (line 12 in customParseFormat.js). The line should be: const matchWord = /\d*[^-_:/.,()\s\d]+/0.

But there is a problem with this solution: unluckily the definitions for monthsShort in the locale definition files are not consistent. Some have a dot at the end, some not; I think that is the reason, why until now the dot is not part of the matchWord regex.

The customization example in the documentation does not have a dot after the monthShort so this looks like a recommendation to me.

There are a few issues concerning the parsing of dots, so perhaps it would be a good idea to make this change. But then we have to remove the dot from the monthShort in all locales (or remove the trailing dot by code in the function getLocalePart in ‘customParseFormat.js’ what would be my recommendation).

This is a decision to be made by @iamkun.

[BePo65]

aah, you got it; the dot is handled by dayjs parsing as a format token and not as a ‘separator’.

At the moment I cannot test it on my sytem, so would you please try, if the dot in the format string can be escaped (surrounded by square brackets)?