Javascript RegEx Help

Question

Can someone help me to validate the following rules using a RegEx pattern

Max length : 15
Minimum length : 6
Minimum character count : 1
Minimum numbers count : 1
Consequent repeated character count : 2

Answer 1

I suggest you use a few different regex patterns to check for all those rules cause it will either be impossible or very complicated.

• .length to check the first 2 rules
• [a-z] (with case insensitive option) for the 3rd rule
• \d for the 4th rule
• (.)\1{2,} for the 5th rule, if this one matches the string contains 3+ character repetitions

Answer 2

^                   # start of string
(?=.{6,15}$)        # assert length
(?=.*[A-Za-z])      # assert letter
(?=.*[0-9])         # assert digit
(?:(.)(?!\1\1))*    # assert no more than 2 consecutive characters
$                   # end of string

will do this. But this won't look nice (or easily maintainable) in JavaScript:

if (/^(?=.{6,15}$)(?=.*[A-Za-z])(?=.*[0-9])(?:(.)(?!\1\1))*$/.test(subject)) {
    // Successful match
} else {
    // Match attempt failed
}