more strict String Parser regex

[FourwingsY]

Describe the bug

from REGEX_PARSE = /^(\d{4})[-/]?(\d{1,2})?[-/]?(\d{0,2})[^0-9]*(\d{1,2})?:?(\d{1,2})?:?(\d{1,2})?[.:]?(\d+)?$/

when new Date('2020.05.23') is parsed in chrome2020-05-23T00:00:00.000, and Invalid in safari.
but dayjs('2020.05.23') is parsing as 2020-01-01T05:00:00.023

Expected behavior

dayjs('2020.05.23') should fallback to native Date

Information

I think the problem is that [^0-9]* accepts any characters including .
what commonly used cases are [Tt\s]*, and it seems okay to me.

[iamkun]

would you like to submit a PR with unit test to fix this?

[FourwingsY]

I have found that dots are not a valid rule from ISO8601 or things, but it just worked in Chrome only.
So It means, It should not matched in REGEX, and fallback to Date

[FourwingsY]

Fix merged