CODEWITHSUNDEEP
javascriptreactjsregexfrontend
Getban
Getban

Reputation: 41

Regex validation

Minimum 3 characters, all small case, can use maximum of 2 numbers, no special characters allowed. I tried using ^[a-zA-Z0-9]*$ but I'm unable to limit the numbers used

Can someone help me.

Upvotes: 1

Views: 392

Answers (2)

The fourth bird
The fourth bird

Reputation: 163217

You could use check if there are at least 3 allowed characters, and then match 0, 1 or 2 digits.

^(?=[A-Za-z\d]{3})[A-Za-z]*(?:\d[A-Za-z]*){0,2}$

Explanation

  • ^ Start of string
  • (?=[A-Za-z\d]{3}) Positive lookahead, assert 3 allowed chars
  • [A-Za-z]* Match optional chars A-Za-z
  • (?:\d[A-Za-z]*){0,2} Repeat 0-2 times matching a single digit and optional chars A-Za-z
  • $ End of string

See the matches on regex101.

Upvotes: 0

Tim Biegeleisen
Tim Biegeleisen

Reputation: 520968

You could use a negative lookahead assertion to rule out more than 3 digits:

/^(?!(?:.*\d+){3,})[a-z0-9]{3,}$/

Here is an explanation of the pattern:

  • ^ from the start of the string
  • (?!(?:.*\d+){3,}) assert that 3 or more digits do NOT occur
  • [a-z0-9]{3,} then match 3 or more lowercase letters or digits
  • $ end of the string

Here is a working demo.

Upvotes: 1

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