Regex Cheatsheet

^

Start of string (or line, with the m flag)

$

End of string (or line, with the m flag)

\b

Word boundary

\B

Not a word boundary

.

Any character except newline

\d

Any digit (0-9)

\D

Any non-digit

\w

Any word character (letters, digits, underscore)

\W

Any non-word character

\s

Any whitespace character

\S

Any non-whitespace character

[abc]

Any one of a, b, or c

[^abc]

Any character except a, b, or c

[a-z]

Any character in the range a to z

*

Zero or more of the preceding token

+

One or more of the preceding token

?

Zero or one of the preceding token

{n}

Exactly n of the preceding token

{n,}

n or more of the preceding token

{n,m}

Between n and m of the preceding token

*?

Zero or more, non-greedy (as few as possible)

+?

One or more, non-greedy (as few as possible)

(abc)

Capturing group

(?:abc)

Non-capturing group

(?<name>abc)

Named capturing group

(a|b)

Match either a or b

(?=abc)

Positive lookahead - followed by abc

(?!abc)

Negative lookahead - not followed by abc

(?<=abc)

Positive lookbehind - preceded by abc

(?<!abc)

Negative lookbehind - not preceded by abc

g

Global - find all matches, not just the first

i

Case-insensitive matching

m

Multiline - ^ and $ match line boundaries

s

Dotall - . also matches newline characters

u

Unicode - enables full Unicode matching

^\d{3}-\d{4}$

A simple phone number format like 555-1234

^[\w.+-]+@[\w-]+\.[\w.-]+$

A basic email address pattern

^https?:\/\/\S+$

A basic URL starting with http or https

^\d{4}-\d{2}-\d{2}$

A date in YYYY-MM-DD format