CODEWITHSUNDEEP
regex
ao-pack
ao-pack

Reputation: 27

Regular expression with alpha, hyphens, underscore and dots characters

I've wrote a regex: 

/^[a-zA-Z\-\_\. ]{2,60}$/

It does work fine-ish however it allows --- or ___ or ... or even -_. to be entered as an input (without 2 alpha at least) and I don't want that. For instance I can have -aa, a-a, aa--- (similarly for the other characters).

The requirement is that there should be at least 2 alpha in the string, and the hyphens and the other 2 non-alpha symbols mentioned can be anywhere inside the string.

Upvotes: 1

Views: 127

Answers (1)

Wiktor Stribiżew
Wiktor Stribiżew

Reputation: 627335

Use

/^(?=(?:[^a-zA-Z]*[a-zA-Z]){2})[-_. a-zA-Z]{2,60}$/

See the regex demo

Details:

  • ^ - start of string
  • (?=(?:[^a-zA-Z]*[a-zA-Z]){2}) - at least 2 alpha chars in the string (that is, there must be exactly 2 consecutive occurrences of:
    • [^a-zA-Z]* - zero or more chars other than ASCII letters
    • [a-zA-Z] - an ASCII letter)
  • [-_. a-zA-Z]{2,60} - 2 to 60 occurrences of allowed chars
  • $ - end of string

Note you do not need to escape - if it is at the start/end of the character class. _ is a word char, no need escaping it anywhere. The . does not need escaping inside a character class.

To tell the regex engine to limit ., _ and - chars to max 10 in the string, add (?!(?:[^._-]*[._-]){11}) negative lookahead after ^ anchor:

/^(?!(?:[^._-]*[._-]){11})(?=(?:[^a-zA-Z]*[a-zA-Z]){2})[-_. a-zA-Z]{2,60}$/

Upvotes: 1

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