Add exact digits patterns (#916)

[yesl-kim]

description

• Issue fixes Correct way to validate time #916
• Added a new pattern: exactNDigits
• Modified HH, mm, ss parser to use exact digits patterns.

comment

• I feagured out that the original flexible digit patterns (twoDigits, threeDigits, fourDigits) are pretty universally used, including y and Y, as well as the thing kind of mm.
• It seems that a new pattern needs to be added to make the y, Y format also check the digit strictly as they said in the issue.
• But first of all, I wanted to ask your opinion, so I modified only the pattern of mm, ss, and hh format that people need the most in that issue.
• Do you agree to be revised in this direction?

Plus

• In moment.js, strictly can be chosen with a third argument.

moment('04:3:00', 'HH:mm:ss', true) // strict
moment('04:3:00', 'HH:mm:ss') // not strict

• I think it's better for backward compatibility
• what do think of it?

[kossnocorp]

I like where it's going! Strict parsing is one of the most requested features, and I want to see it addressed. The way to go is to hide it behind the strict option and make it strict in the next major version by default.

Feel free to complete the PR by adding the option and expanding the approach to the rest of the numeric tokens!

[yesl-kim]

@kossnocorp Thank you for comment!

changes

• Added new patterns and utils for strict mode
  • minNDigits: specifies only padding (eg. yyy -> 001, 012, 123, 1234, ...)
  • exactNDigits: specifies the maximum length as well as padding
• Modified it to parse strictly as options

comment

• Normally used minNDigits pattern since the validate method is checking the range of values.
• Tested all tokens I modified but wrote the part of them randomly since they're mostly the same.