regex101: JavaScript Match Workspace

1st Alternative^(I[VX]|VI{0,3}|I{1,3})

^start of line

Group 1(I[VX]|VI{0,3}|I{1,3})

1st AlternativeI[VX]

Ithe literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive)

Character Class[VX]

Vthe literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

Xthe literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive)

2nd AlternativeVI{0,3}

Vthe literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

I{0,3}the literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive), repeated between 0 and 3 times

3rd AlternativeI{1,3}

I{1,3}the literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive), repeated between 1 and 3 times

2nd Alternative((X[LC]|LX{0,3}|X{1,3})(I[VX]|V?I{0,3}))

Group 2((X[LC]|LX{0,3}|X{1,3})(I[VX]|V?I{0,3}))

Group 3(X[LC]|LX{0,3}|X{1,3})

1st AlternativeX[LC]

Xthe literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive)

Character Class[LC]

Lthe literal L (76₁₀ / 114₈ / 4C₁₆) (case sensitive)

Cthe literal C (67₁₀ / 103₈ / 43₁₆) (case sensitive)

2nd AlternativeLX{0,3}

Lthe literal L (76₁₀ / 114₈ / 4C₁₆) (case sensitive)

X{0,3}the literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive), repeated between 0 and 3 times

3rd AlternativeX{1,3}

X{1,3}the literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive), repeated between 1 and 3 times

Group 4(I[VX]|V?I{0,3})

1st AlternativeI[VX]

Ithe literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive)

Character Class[VX]

Vthe literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

Xthe literal X (88₁₀ / 130₈ / 58₁₆) (case sensitive)

2nd AlternativeV?I{0,3}

V?optionally matches the literal V (86₁₀ / 126₈ / 56₁₆) (case sensitive)

I{0,3}the literal I (73₁₀ / 111₈ / 49₁₆) (case sensitive), repeated between 0 and 3 times

3rd Alternative((C[DM]|DC{0,3}|C{1,3})(X[LC]|L?X{0,3})(I[VX]|V?I{0,3}))

Group 5((C[DM]|DC{0,3}|C{1,3})(X[LC]|L?X{0,3})(I[VX]|V?I{0,3}))

Group 6(C[DM]|DC{0,3}|C{1,3})

1st AlternativeC[DM]

Cthe literal C (67₁₀ / 103₈ / 43₁₆) (case sensitive)

Character Class[DM]

Dthe literal D (68₁₀ / 104₈ / 44₁₆) (case sensitive)

Mthe literal M (77₁₀ / 115₈ / 4D₁₆) (case sensitive)

2nd AlternativeDC{0,3}

Dthe literal D (68₁₀ / 104₈ / 44₁₆) (case sensitive)

C{0,3}the literal C (67₁₀ / 103₈ / 43₁₆) (case sensitive), repeated between 0 and 3 times

3rd AlternativeC{1,3}

C{1,3}the literal C (67₁₀ / 103₈ / 43₁₆) (case sensitive), repeated between 1 and 3 times

Group 7(X[LC]|L?X{0,3})

1st AlternativeX[LC]

2nd AlternativeL?X{0,3}

Group 8(I[VX]|V?I{0,3})

4th Alternative(M+(C[DM]|D?C{0,3})(X[LC]|L?X{0,3})(I[VX]|V?I{0,3}))$

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

26 tokens

Regular Expression

^(I[VX]|VI{0,3}|I{1,3})|((X[LC]|LX{0,3}|X{1,3})(I[VX]|V?I{0,3}))|((C[DM]|DC{0,3}|C{1,3})(X[LC]|L?X{0,3})(I[VX]|V?I{0,3}))|(M+(C[DM]|D?C{0,3})(X[LC]|L?X{0,3})(I[VX]|V?I{0,3}))$

New

I
II
III
IV
V
VI
VII
VIII
IX
X
XI
XII
XIII
XIV
XV
XVI
XVII
XVIII
XIX
XX
XLIV
XLIX
LXXIX
XCIV
XCIX
C
CI
CII
CIII
CIV
CVI
CIX
CD
CM
CC
CCC
D
DC
DCC
DCCC
CX
CXX
CXIX
CMXCIX
MCMXLIV
MMMMCCCXII

Regular Expressions 101

Regular Expression

Substitution