Regex Cheatsheet

Quick reference for regular expression syntax, flags, and common patterns.

Anchors

^Start of string

$End of string

\bWord boundary

\BNon-word boundary

Character Classes

.Any character except newline

\dDigit [0-9]

\DNon-digit

\wWord char [a-zA-Z0-9_]

\WNon-word char

\sWhitespace

\SNon-whitespace

Quantifiers

*0 or more

+1 or more

?0 or 1 (optional)

{n}Exactly n times

{n,}n or more times

{n,m}Between n and m

*?Lazy (non-greedy)

Groups

(abc)Capture group

(?:abc)Non-capture group

(?<name>)Named capture

\1Backreference group 1

(?=abc)Positive lookahead

(?!abc)Negative lookahead

Sets

[abc]Any of a, b, or c

[^abc]Not a, b, or c

[a-z]Range a through z

[a-zA-Z]Any letter

Flags

gGlobal (all matches)

iCase-insensitive

mMultiline (^ and $ per line)

sDot matches newline

uUnicode mode

Common Patterns

\d{4}-\d{2}-\d{2}Date YYYY-MM-DD

[\w.-]+@[\w.-]+\.\w+Email (simple)

https?:\/\/\S+URL

\b\d{1,3}(\.\d{1,3}){3}\bIPv4 address

Frequently Asked Questions

: The cheat sheet covers JavaScript/ECMAScript regex syntax, which is also largely compatible with Python, Java, and most modern languages.