Regex Cheat Sheet

Searchable regular expression cheat sheet organized by category. Covers anchors, quantifiers, character classes, groups, flags, and common patterns with one-click copy.

How to UseExpand how to use

1
Search or filter by category
Enter a pattern or keyword in the search field, or click a category button (Anchors, Quantifiers, etc.) to narrow down the list.
2
Review description and examples
Check each pattern's description, usage example, and expected output to understand how it works.
3
Copy the pattern
Click the copy button on any card to copy the pattern to your clipboard for immediate use in your code or terminal.

^
Match at the start of a string (or line with m flag)

Example

/^Hello/.test('Hello World')

Output

true

$
Match at the end of a string (or line with m flag)

Example

/World$/.test('Hello World')

Output

true

\b
Match a word boundary (between word and non-word character)

Example

'cat catalog'.match(/\bcat\b/g)

Output

['cat']

\B
Match a non-word boundary

Example

'catalog'.match(/\Bcat\B/g)

Output

null

*
Match 0 or more occurrences of the preceding element

Example

'color colour'.match(/colou*r/g)

Output

['color', 'colour']

+
Match 1 or more occurrences of the preceding element

Example

'ac abc'.match(/ab+c/g)

Output

['abc']

?
Match 0 or 1 occurrence of the preceding element (optional)

Example

'color colour'.match(/colou?r/g)

Output

['color', 'colour']

{n}
Match exactly n occurrences of the preceding element

Example

'aaa aa a'.match(/a{2}/g)

Output

['aa', 'aa']

{n,}
Match n or more occurrences of the preceding element

Example

'aaa aa a'.match(/a{2,}/g)

Output

['aaa', 'aa']

{n,m}
Match between n and m occurrences of the preceding element

Example

'aaaa aaa aa a'.match(/a{2,3}/g)

Output

['aaa', 'aaa', 'aa']

\d
Match any digit character (equivalent to [0-9])

Example

'abc 123'.match(/\d+/g)

Output

['123']

\D
Match any non-digit character (equivalent to [^0-9])

Example

'abc 123'.match(/\D+/g)

Output

['abc ']

\w
Match any word character (equivalent to [A-Za-z0-9_])

Example

'hello world_2'.match(/\w+/g)

Output

['hello', 'world_2']

\W
Match any non-word character (equivalent to [^A-Za-z0-9_])

Example

'hello world'.match(/\W+/g)

Output

[' ']

\s
Match any whitespace character (space, tab, newline, etc.)

Example

'hello world'.match(/\s+/g)

Output

[' ']

\S
Match any non-whitespace character

Example

'hello world'.match(/\S+/g)

Output

['hello', 'world']

[abc]
Match any one character listed in the brackets

Example

'cat bat hat'.match(/[cbh]at/g)

Output

['cat', 'bat', 'hat']

[a-z]
Match any character in the specified range

Example

'Hello World'.match(/[a-z]+/g)

Output

['ello', 'orld']

[^abc]
Match any character not listed in the brackets

Example

'cat 123'.match(/[^\d ]+/g)

Output

['cat']

(...)
Capture a group and allow backreference with $1, $2, etc.

Example

'2024-03-15'.replace(/(\d{4})-(\d{2})-(\d{2})/, '$2/$3/$1')

Output

'03/15/2024'

(?:...)
Group without capturing (more efficient than capturing group)

Example

'foobar foobaz'.match(/foo(?:bar|baz)/g)

Output

['foobar', 'foobaz']

(?=...)
Match only if followed by the specified pattern (not consumed)

Example

'100px 200em'.match(/\d+(?=px)/g)

Output

['100']

(?!...)
Match only if NOT followed by the specified pattern

Example

'100px 200em'.match(/\d+(?!px)/g)

Output

['10', '200']

(?<=...)
Match only if preceded by the specified pattern (not consumed)

Example

'$100 €200'.match(/(?<=\$)\d+/g)

Output

['100']

(?<!...)
Match only if NOT preceded by the specified pattern

Example

'$100 200'.match(/(?<!\$)\d+/g)

Output

['200']

g
Global: find all matches instead of stopping at the first

Example

'aaa'.match(/a/g)

Output

['a', 'a', 'a']

i
Case-insensitive: match regardless of upper/lower case

Example

'Hello HELLO'.match(/hello/gi)

Output

['Hello', 'HELLO']

m
Multiline: ^ and $ match start/end of each line

Example

'line1\nline2'.match(/^line/gm)

Output

['line', 'line']

s
Dotall: . matches newline characters as well

Example

'foo\nbar'.match(/foo.bar/s)

Output

['foo\nbar']

u
Unicode: enables full Unicode support including surrogate pairs

Example

'\u{1F600}'.match(/./u)[0].length

Output

.
Match any single character except newline (use s flag for newline too)

Example

'cat bat'.match(/.at/g)

Output

['cat', 'bat']

a|b
Match either the left or right expression

Example

'cat dog bird'.match(/cat|dog/g)

Output

['cat', 'dog']

\.
Escape a special character to match it literally

Example

'3.14'.match(/3\.14/)

Output

['3.14']

(?<name>...)
Capture a named group, accessible via match.groups.name

Example

'2024-03-15'.match(/(?<y>\d{4})-(?<m>\d{2})-(?<d>\d{2})/).groups

Output

Tools.Reference.RegexCheatsheet.patterns.namedGroup.output

[\w.+\-]+@[\w\-]+\.[a-z]{2,}
Match a basic email address (simplified pattern)

Example

/.+@.+/.test('user@example.com')

Output

true

https?:\/\/[\w\-._~:/?#\[\]@!$&'()*+,;=%]+
Match an HTTP or HTTPS URL

Example

/https?:\/\/.+/.test('https://example.com')

Output

true

0\d{1,4}-\d{1,4}-\d{4}
Match a Japanese phone number format (e.g. 03-1234-5678)

Example

/0\d{1,4}-\d{1,4}-\d{4}/.test('03-1234-5678')

Output

true

(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)
Match a valid IPv4 address (0.0.0.0 – 255.255.255.255)

Example

/valid IPv4 pattern/.test('192.168.1.1')

Output

true

\d{4}[-/](?:0[1-9]|1[0-2])[-/](?:0[1-9]|[12]\d|3[01])
Match a date in YYYY-MM-DD or YYYY/MM/DD format

Example

/\d{4}[-\/]\d{2}[-\/]\d{2}/.test('2024-03-15')

Output

true

#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6})\b
Match a CSS hex color code (#RGB or #RRGGBB)

Example

'color: #fff and #1a2b3c'.match(/#[0-9a-fA-F]{3,6}/g)

Output

['#fff', '#1a2b3c']

\d{3}-\d{4}
Match a Japanese postal code (e.g. 123-4567)

Example

/\d{3}-\d{4}/.test('123-4567')

Output

true

About Regex Cheat Sheet

Regex Cheat Sheet is a quick reference for regular expression syntax. It covers all major constructs including anchors, quantifiers, character classes, capturing groups, lookahead/lookbehind assertions, and flags. Common real-world patterns for email, URL, IP address, and date formats are also included. Each entry provides a practical example with expected output.

Key Features

40+ essential regex patterns across 7 categories
Practical example and expected output for each pattern
Category filtering (anchors, quantifiers, char classes, etc.)
Real-time search by pattern or description
One-click copy of any pattern

Use Cases

Quick syntax lookup while writing regex in code
Learning regex fundamentals and special constructs
Copying ready-made patterns for email, URL, or date validation
Refreshing knowledge of lookahead and lookbehind assertions
Reference during code review or pair programming

FAQ

What is the difference between * and +?

* matches 0 or more occurrences, while + requires at least 1. For example, /ab*c/ matches 'ac', 'abc', 'abbc', but /ab+c/ only matches 'abc', 'abbc' — not 'ac'.

What is the difference between a capturing group (...) and a non-capturing group (?:...)?

A capturing group stores the matched text and makes it available as $1, $2, etc. in replacements or match.groups. A non-capturing group only groups for precedence and quantifiers without storing the match, which is more efficient.

What is the difference between lookahead (?=...) and lookbehind (?<=...)?

Lookahead (?=...) asserts that the pattern must follow the current position. Lookbehind (?<=...) asserts that the pattern must precede the current position. Neither consumes characters, so they are called zero-width assertions.

What does the g flag do?

The g (global) flag makes the regex engine find all matches in the string instead of stopping after the first. Without g, methods like String.match() return only the first match.

How do I match a literal dot or other special character?

Escape it with a backslash. For example, use \. to match a literal dot, \( to match a literal parenthesis, and \* to match a literal asterisk. Without the backslash, . matches any character.

Regex Cheat Sheet

Searchable regular expression cheat sheet organized by category. Covers anchors, quantifiers, character classes, groups, flags, and common patterns with one-click copy.

How to UseExpand how to use

1
Search or filter by category
Enter a pattern or keyword in the search field, or click a category button (Anchors, Quantifiers, etc.) to narrow down the list.
2
Review description and examples
Check each pattern's description, usage example, and expected output to understand how it works.
3
Copy the pattern
Click the copy button on any card to copy the pattern to your clipboard for immediate use in your code or terminal.

^
Match at the start of a string (or line with m flag)

Example

/^Hello/.test('Hello World')

Output

true

$
Match at the end of a string (or line with m flag)

Example

/World$/.test('Hello World')

Output

true

\b
Match a word boundary (between word and non-word character)

Example

'cat catalog'.match(/\bcat\b/g)

Output

['cat']

\B
Match a non-word boundary

Example

'catalog'.match(/\Bcat\B/g)

Output

null

*
Match 0 or more occurrences of the preceding element

Example

'color colour'.match(/colou*r/g)

Output

['color', 'colour']

+
Match 1 or more occurrences of the preceding element

Example

'ac abc'.match(/ab+c/g)

Output

['abc']

?
Match 0 or 1 occurrence of the preceding element (optional)

Example

'color colour'.match(/colou?r/g)

Output

['color', 'colour']

{n}
Match exactly n occurrences of the preceding element

Example

'aaa aa a'.match(/a{2}/g)

Output

['aa', 'aa']

{n,}
Match n or more occurrences of the preceding element

Example

'aaa aa a'.match(/a{2,}/g)

Output

['aaa', 'aa']

{n,m}
Match between n and m occurrences of the preceding element

Example

'aaaa aaa aa a'.match(/a{2,3}/g)

Output

['aaa', 'aaa', 'aa']

\d
Match any digit character (equivalent to [0-9])

Example

'abc 123'.match(/\d+/g)

Output

['123']

\D
Match any non-digit character (equivalent to [^0-9])

Example

'abc 123'.match(/\D+/g)

Output

['abc ']

\w
Match any word character (equivalent to [A-Za-z0-9_])

Example

'hello world_2'.match(/\w+/g)

Output

['hello', 'world_2']

\W
Match any non-word character (equivalent to [^A-Za-z0-9_])

Example

'hello world'.match(/\W+/g)

Output

[' ']

\s
Match any whitespace character (space, tab, newline, etc.)

Example

'hello world'.match(/\s+/g)

Output

[' ']

\S
Match any non-whitespace character

Example

'hello world'.match(/\S+/g)

Output

['hello', 'world']

[abc]
Match any one character listed in the brackets

Example

'cat bat hat'.match(/[cbh]at/g)

Output

['cat', 'bat', 'hat']

[a-z]
Match any character in the specified range

Example

'Hello World'.match(/[a-z]+/g)

Output

['ello', 'orld']

[^abc]
Match any character not listed in the brackets

Example

'cat 123'.match(/[^\d ]+/g)

Output

['cat']

(...)
Capture a group and allow backreference with $1, $2, etc.

Example

'2024-03-15'.replace(/(\d{4})-(\d{2})-(\d{2})/, '$2/$3/$1')

Output

'03/15/2024'

(?:...)
Group without capturing (more efficient than capturing group)

Example

'foobar foobaz'.match(/foo(?:bar|baz)/g)

Output

['foobar', 'foobaz']

(?=...)
Match only if followed by the specified pattern (not consumed)

Example

'100px 200em'.match(/\d+(?=px)/g)

Output

['100']

(?!...)
Match only if NOT followed by the specified pattern

Example

'100px 200em'.match(/\d+(?!px)/g)

Output

['10', '200']

(?<=...)
Match only if preceded by the specified pattern (not consumed)

Example

'$100 €200'.match(/(?<=\$)\d+/g)

Output

['100']

(?<!...)
Match only if NOT preceded by the specified pattern

Example

'$100 200'.match(/(?<!\$)\d+/g)

Output

['200']

g
Global: find all matches instead of stopping at the first

Example

'aaa'.match(/a/g)

Output

['a', 'a', 'a']

i
Case-insensitive: match regardless of upper/lower case

Example

'Hello HELLO'.match(/hello/gi)

Output

['Hello', 'HELLO']

m
Multiline: ^ and $ match start/end of each line

Example

'line1\nline2'.match(/^line/gm)

Output

['line', 'line']

s
Dotall: . matches newline characters as well

Example

'foo\nbar'.match(/foo.bar/s)

Output

['foo\nbar']

u
Unicode: enables full Unicode support including surrogate pairs

Example

'\u{1F600}'.match(/./u)[0].length

Output

.
Match any single character except newline (use s flag for newline too)

Example

'cat bat'.match(/.at/g)

Output

['cat', 'bat']

a|b
Match either the left or right expression

Example

'cat dog bird'.match(/cat|dog/g)

Output

['cat', 'dog']

\.
Escape a special character to match it literally

Example

'3.14'.match(/3\.14/)

Output

['3.14']

(?<name>...)
Capture a named group, accessible via match.groups.name

Example

'2024-03-15'.match(/(?<y>\d{4})-(?<m>\d{2})-(?<d>\d{2})/).groups

Output

Tools.Reference.RegexCheatsheet.patterns.namedGroup.output

[\w.+\-]+@[\w\-]+\.[a-z]{2,}
Match a basic email address (simplified pattern)

Example

/.+@.+/.test('user@example.com')

Output

true

https?:\/\/[\w\-._~:/?#\[\]@!$&'()*+,;=%]+
Match an HTTP or HTTPS URL

Example

/https?:\/\/.+/.test('https://example.com')

Output

true

0\d{1,4}-\d{1,4}-\d{4}
Match a Japanese phone number format (e.g. 03-1234-5678)

Example

/0\d{1,4}-\d{1,4}-\d{4}/.test('03-1234-5678')

Output

true

(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)
Match a valid IPv4 address (0.0.0.0 – 255.255.255.255)

Example

/valid IPv4 pattern/.test('192.168.1.1')

Output

true

\d{4}[-/](?:0[1-9]|1[0-2])[-/](?:0[1-9]|[12]\d|3[01])
Match a date in YYYY-MM-DD or YYYY/MM/DD format

Example

/\d{4}[-\/]\d{2}[-\/]\d{2}/.test('2024-03-15')

Output

true

#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6})\b
Match a CSS hex color code (#RGB or #RRGGBB)

Example

'color: #fff and #1a2b3c'.match(/#[0-9a-fA-F]{3,6}/g)

Output

['#fff', '#1a2b3c']

\d{3}-\d{4}
Match a Japanese postal code (e.g. 123-4567)

Example

/\d{3}-\d{4}/.test('123-4567')

Output

true

About Regex Cheat Sheet

Key Features

40+ essential regex patterns across 7 categories
Practical example and expected output for each pattern
Category filtering (anchors, quantifiers, char classes, etc.)
Real-time search by pattern or description
One-click copy of any pattern

Use Cases

Quick syntax lookup while writing regex in code
Learning regex fundamentals and special constructs
Copying ready-made patterns for email, URL, or date validation
Refreshing knowledge of lookahead and lookbehind assertions
Reference during code review or pair programming

FAQ

What is the difference between * and +?

* matches 0 or more occurrences, while + requires at least 1. For example, /ab*c/ matches 'ac', 'abc', 'abbc', but /ab+c/ only matches 'abc', 'abbc' — not 'ac'.

What is the difference between a capturing group (...) and a non-capturing group (?:...)?

What is the difference between lookahead (?=...) and lookbehind (?<=...)?

What does the g flag do?

The g (global) flag makes the regex engine find all matches in the string instead of stopping after the first. Without g, methods like String.match() return only the first match.

How do I match a literal dot or other special character?

Escape it with a backslash. For example, use \. to match a literal dot, \( to match a literal parenthesis, and \* to match a literal asterisk. Without the backslash, . matches any character.

Regex Cheat Sheet

Search or filter by category

Review description and examples

Copy the pattern

^Match at the start of a string (or line with m flag)

Example

Output

$Match at the end of a string (or line with m flag)

Example

Output

\bMatch a word boundary (between word and non-word character)

Example

Output

\BMatch a non-word boundary

Example

Output

*Match 0 or more occurrences of the preceding element

Example

Output

+Match 1 or more occurrences of the preceding element

Example

Output

?Match 0 or 1 occurrence of the preceding element (optional)

Example

Output

{n}Match exactly n occurrences of the preceding element

Example

Output

{n,}Match n or more occurrences of the preceding element

Example

Output

{n,m}Match between n and m occurrences of the preceding element

Example

Output

\dMatch any digit character (equivalent to [0-9])

Example

Output

\DMatch any non-digit character (equivalent to [^0-9])

Example

Output

\wMatch any word character (equivalent to [A-Za-z0-9_])

Example

Output

\WMatch any non-word character (equivalent to [^A-Za-z0-9_])

Example

Output

\sMatch any whitespace character (space, tab, newline, etc.)

Example

Output

\SMatch any non-whitespace character

Example

Output

[abc]Match any one character listed in the brackets

Example

Output

[a-z]Match any character in the specified range

Example

Output

[^abc]Match any character not listed in the brackets

Example

Output

(...)Capture a group and allow backreference with $1, $2, etc.

Example

Output

(?:...)Group without capturing (more efficient than capturing group)

Example

Output

(?=...)Match only if followed by the specified pattern (not consumed)

Example

Output

(?!...)Match only if NOT followed by the specified pattern

Example

Output

(?<=...)Match only if preceded by the specified pattern (not consumed)

Example

Output

(?<!...)Match only if NOT preceded by the specified pattern

Example

Output

gGlobal: find all matches instead of stopping at the first

^
Match at the start of a string (or line with m flag)

$
Match at the end of a string (or line with m flag)

\b
Match a word boundary (between word and non-word character)

\B
Match a non-word boundary

*
Match 0 or more occurrences of the preceding element

+
Match 1 or more occurrences of the preceding element

?
Match 0 or 1 occurrence of the preceding element (optional)

{n}
Match exactly n occurrences of the preceding element

{n,}
Match n or more occurrences of the preceding element

{n,m}
Match between n and m occurrences of the preceding element

\d
Match any digit character (equivalent to [0-9])

\D
Match any non-digit character (equivalent to [^0-9])

\w
Match any word character (equivalent to [A-Za-z0-9_])

\W
Match any non-word character (equivalent to [^A-Za-z0-9_])

\s
Match any whitespace character (space, tab, newline, etc.)

\S
Match any non-whitespace character

[abc]
Match any one character listed in the brackets

[a-z]
Match any character in the specified range

[^abc]
Match any character not listed in the brackets

(...)
Capture a group and allow backreference with $1, $2, etc.

(?:...)
Group without capturing (more efficient than capturing group)

(?=...)
Match only if followed by the specified pattern (not consumed)

(?!...)
Match only if NOT followed by the specified pattern

(?<=...)
Match only if preceded by the specified pattern (not consumed)

(?<!...)
Match only if NOT preceded by the specified pattern

g
Global: find all matches instead of stopping at the first

i
Case-insensitive: match regardless of upper/lower case

m
Multiline: ^ and $ match start/end of each line

s
Dotall: . matches newline characters as well

u
Unicode: enables full Unicode support including surrogate pairs

.
Match any single character except newline (use s flag for newline too)

a|b
Match either the left or right expression

\.
Escape a special character to match it literally

(?<name>...)
Capture a named group, accessible via match.groups.name

[\w.+\-]+@[\w\-]+\.[a-z]{2,}
Match a basic email address (simplified pattern)

https?:\/\/[\w\-._~:/?#\[\]@!$&'()*+,;=%]+
Match an HTTP or HTTPS URL

0\d{1,4}-\d{1,4}-\d{4}
Match a Japanese phone number format (e.g. 03-1234-5678)

(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)\.(?:25[0-5]|2[0-4]\d|[01]?\d\d?)
Match a valid IPv4 address (0.0.0.0 – 255.255.255.255)

\d{4}[-/](?:0[1-9]|1[0-2])[-/](?:0[1-9]|[12]\d|3[01])
Match a date in YYYY-MM-DD or YYYY/MM/DD format

#(?:[0-9a-fA-F]{3}|[0-9a-fA-F]{6})\b
Match a CSS hex color code (#RGB or #RRGGBB)

\d{3}-\d{4}
Match a Japanese postal code (e.g. 123-4567)

^
Match at the start of a string (or line with m flag)

$
Match at the end of a string (or line with m flag)

\b
Match a word boundary (between word and non-word character)

\B
Match a non-word boundary

*
Match 0 or more occurrences of the preceding element