CODEWITHSUNDEEP
javascriptregexregex-negation
BKlassen
BKlassen

Reputation: 160

How to negate a regex pattern

So I have a regex that identifies an invalid pattern for my input, I would like to be able to reverse it so that instead of matching invalid cases it matches with valid cases. Here is the invalid regex: 

^(?=\d{6}$)(?:(\d)\1{5,}|012345|123456|234567|345678|456789|567890|098765|987654|876543|765432|654321|54321)$

Ideally to match positive cases it should ensure:

I have tried replacing the non capture group with a negative lookahead, however as I'm not familiar with the finer syntax for regex I'm not positive if this is simply an input mistake or if I need to change the regex somewhere else

EDITS While I know this could be handled by javascript I would like to handle it with regex to leverage the Foundations error handling

Upvotes: 1

Views: 267

Answers (1)

Poul Bak
Poul Bak

Reputation: 10940

You can use this regex:

/(?=^(\d){6}$)(?!^\1{6})(?!^(?:012345|123456|234567|345678|456789|567890|098765|987654|876543|765432|654321|54321)$)^\d+$/

The regex uses look ahead and starts by checking there's 6 digits. It captures the last digit which is used with a back reference to check, there's not 6 of the same digit. It then use a negative look ahead to compare with the list of invalid sequences.

Finally it matches the 6 digits.

Upvotes: 2

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