regex101: JavaScript Match Workspace

^start of line

Negative Lookahead(?!(?:0(?:\.0){3}|255(?:\.255){3})$)

Non-Capturing Group(?:0(?:\.0){3}|255(?:\.255){3})

1st Alternative0(?:\.0){3}

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

Non-Capturing Group(?:\.0){3}

{3}repeats the group contents below exactly 3 times:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

2nd Alternative255(?:\.255){3}

255the literal text 255

Non-Capturing Group(?:\.255){3}

{3}repeats the group contents below exactly 3 times:

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

255the literal text 255

$end of line

Group 1([01]?\d\d?|2[0-4]\d|25[0-5])

1st Alternative[01]?\d\d?

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

\d?optionally matches a digit

2nd Alternative2[0-4]\d

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

0-4one character from 0 (48₁₀) to 4 (52₁₀)

\da digit

3rd Alternative25[0-5]

25the literal text 25

Character Class[0-5]

0-5one character from 0 (48₁₀) to 5 (53₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 2([01]?\d\d?|2[0-4]\d|25[0-5])

1st Alternative[01]?\d\d?

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

\d?optionally matches a digit

2nd Alternative2[0-4]\d

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

0-4one character from 0 (48₁₀) to 4 (52₁₀)

\da digit

3rd Alternative25[0-5]

25the literal text 25

Character Class[0-5]

0-5one character from 0 (48₁₀) to 5 (53₁₀)

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 3([01]?\d\d?|2[0-4]\d|25[0-5])

1st Alternative[01]?\d\d?

Character Class[01]?

?matches at most one character from the set below:

0the literal 0 (48₁₀ / 60₈ / 30₁₆)

1the literal 1 (49₁₀ / 61₈ / 31₁₆)

\da digit

\d?optionally matches a digit

2nd Alternative2[0-4]\d

2the literal 2 (50₁₀ / 62₈ / 32₁₆)

Character Class[0-4]

0-4one character from 0 (48₁₀) to 4 (52₁₀)

\da digit

3rd Alternative25[0-5]

\.the literal . (46₁₀ / 56₈ / 2E₁₆)

Group 4([01]?\d\d?|2[0-4]\d|25[0-5])

$end of line

Global pattern flags

g modifier: global. Finds all matches instead of stopping after the first

m modifier: multiline. Causes ^ and $ to match the start and end of each line, not only the start and end of the string

Search reference

Regular Expression

^(?!(?:0(?:\.0){3}|255(?:\.255){3})$)([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])\.([01]?\d\d?|2[0-4]\d|25[0-5])$

Test String
New

100.1.2.3
0.0.0.0
0.0.0.1
255.255.255.254
255.255.255.255
255.255.255.256

Regular Expressions 101

Regular Expression

Test String
New

Substitution
Processing...

Regular Expression

Test StringNew

SubstitutionProcessing...

Test String
New

Substitution
Processing...