Regex

[inharest]

Syntax

Meta characters

Metacharacter	Description
|	Separates alternate possibilities.
^	Matches the beginning of a line or string.
$	Matches the end of a line or string.
[ ]	Matches every character inside brackets.
.	Matches any single character.
\w	Matches an alphanumeric character.
\s	Matches a whitespace character.
\d	Matches a digit.
\b	Matches a word boundary.

Antisense characters

Metacharacter	Description
[^ ]	Matches every character except inside brackets.
\W	Matches a non-alphanumeric character.
\S	Matches anything but a whitespace.
\D	Matches a non-digit.
\B	Matches a non-word boundary.

Escape characters

Metacharacter	Description
\f	Matches a form feed (U+000C).
\n	Matches a line feed (U+000A).
\r	Matches a carriage return (U+000D).
\t	Matches a tab (U+0009).
\v	Matches a vertical tab (U+000B).
\xhh	Matches the character with the code hh (two hexadecimal digits).
\uhhhh	Matches the character with the code hhhh (four hexadecimal digits).

Greed

Metacharacter	Description
?	Matches the preceding pattern element zero or one time.
*	Matches the preceding pattern element zero or more times.
+	Matches the preceding pattern element one or more times.
{N}	Matches the preceding pattern element N times.
{N, }	Matches the preceding pattern element N or more times.
{M, N}	Matches the preceding pattern element at least M times, but not more than max times.

Laziness

Metacharacter	Description
?	Modifies the *, +, ? or {M,N}'d regex that comes before to match as few times as possible.
??	Matches ? time, match as few times as possible.
*?	Matches * time, match as few times as possible.
+?	Matches + time, match as few times as possible.
{M, N}?	Matches {M, N} time, match as few times as possible.

Grouping

Metacharacter	Description
( )	Groups a series of pattern elements to a single element.
(exp)	Matches exp and remembers the match.
(?:exp1)	Matches exp but does not remember the match.
exp1(?=exp2)	Matches exp1 only if exp1 is followed by exp2. This is called a lookahead.
exp1(?!exp2)	Matches exp1 only if exp1 is not followed by exp2. This is called a negated lookahead.

Modifier

Flag	Description
g	Global search.
i	Case-insensitive search.
m	Multi-line search.

References

Regular expression - wikipedia Regular Expressions - MDN Regular expressions 正则表达式30分钟入门教程

Visualize

Regulex Regexper Debuggex