正規表現チートシート

Any single character except newline

a.c → 'abc'

Digit (0-9)

\d+ → '123'

Non-digit

\D+ → 'abc'

Word char [A-Za-z0-9_]

\w+ → 'foo_1'

Non-word char

\W → '!'

Whitespace (space, tab, newline)

a\sb → 'a b'

Non-whitespace

\S+ → 'foo'

Word boundary

\bcat\b → 'cat'

Non-word boundary

\Bcat → 'concat'

0 or more (greedy)

a* → '', 'aaa'

1 or more (greedy)

a+ → 'aaa'

0 or 1 (optional)

colou?r → 'color', 'colour'

Exactly n times

\d{4} → '2025'

n or more times

\d{2,} → '12', '123'

Between n and m times

\d{2,4} → '12', '1234'

0 or more (lazy)

<.*?> → '<a>', '<b>'

1 or more (lazy)

.+? → minimal match

Any one of a, b, c

[aeiou] → vowels

None of a, b, c

[^0-9] → non-digit

Range a to z

[A-Za-z] → letters

Combined classes

[\d\.] → digit or dot

Start of string (or line with /m)

^foo → starts with foo

End of string (or line with /m)

bar$ → ends with bar

Capturing group

(\d+)-(\w+) → captures both

Non-capturing group

(?:foo|bar)+

Named capture group

(?<year>\d{4})

Alternation (or)

cat|dog → 'cat' or 'dog'

Backreference to group 1

(\w)\1 → 'oo' in 'book'

Positive lookahead

\d(?=px) → '12' in '12px'

Negative lookahead

\d(?!px) → digit not followed by px

Positive lookbehind

(?<=\$)\d+ → '100' in '$100'

Negative lookbehind

(?<!\$)\d+ → digit not after $

Global — all matches

/foo/g

Case-insensitive

/FOO/i → matches 'foo'

Multiline — ^/$ per line

/^line/m

Dotall — . matches newline

/a.b/s

Unicode mode

/\u{1F600}/u

Sticky — match from lastIndex

/foo/y