チートシート

正規表現チートシート

正規表現の基本構文から応用メタ文字までを一目で確認できる実用リファレンス。

文字クラス

構文	説明	使用例
`.`	Any character except newline	a.c → abc, aXc
`\d`	Any digit (0-9)	\d+ → 123, 42
`\D`	Any non-digit	\D+ → abc, !@#
`\w`	Word character (letter, digit, underscore)	\w+ → hello_42
`\W`	Non-word character	\W → @, !, space
`\s`	Any whitespace (space, tab, newline)	\s → space, tab
`\S`	Any non-whitespace	\S+ → hello
`[abc]`	Any one of a, b, or c	[aeiou] → vowels
`[^abc]`	Any character except a, b, or c	[^0-9] → non-digits
`[a-z]`	Any character in range a to z	[a-zA-Z] → letters
`[0-9]`	Any digit (same as \d)	[0-9]{3} → 123

構文	説明	使用例
`^`	Start of string (or line with m flag)	^Hello → starts with Hello
`$`	End of string (or line with m flag)	world$ → ends with world
`\b`	Word boundary	\bword\b → whole word
`\B`	Non-word boundary	\Bword → mid-word

構文	説明	使用例
`(?=abc)`	Positive lookahead — followed by abc	\d(?=px) → digit before px
`(?!abc)`	Negative lookahead — NOT followed by abc	\d(?!px) → digit not before px
`(?<=abc)`	Positive lookbehind — preceded by abc	(?<=\$)\d+ → digits after $
`(?<!abc)`	Negative lookbehind — NOT preceded by abc	(?<!\$)\d+ → digits not after $

構文	説明	使用例
`g`	Global — find all matches	/regex/g
`i`	Case-insensitive	/hello/i → Hello, HELLO
`m`	Multiline — ^ and $ match line boundaries	/^line/m
`s`	Dotall — . matches newlines too	/a.b/s → a\nb
`u`	Unicode mode	/\p{Letter}/u
`v`	Unicode sets (extended)	/[\p{Letter}]/v
`d`	Generate indices for matches	match.indices
`y`	Sticky — match from lastIndex only	/regex/y