RegEx Cheatsheet

Start of string (or line in multiline mode).

End of string (or line in multiline mode).

Word boundary — position between word and non-word characters.

Non-word boundary.

Start of input (PCRE / .NET / Python, NOT JS).

End of input (PCRE / .NET / Python, NOT JS).

Any character except newline (or any char with the s flag).

Any digit (0-9).

Any non-digit.

Word character: [A-Za-z0-9_].

Non-word character.

Whitespace (space, tab, newline, etc.).

Non-whitespace.

Any one of the listed characters.

Any character NOT in the set.

Range — any lowercase letter.

Range — any digit.

Tab character.

Newline character.

Carriage return.

Character with hex code HH.

Unicode character (4 hex digits).

Unicode property class (requires u flag).

Zero or more of the previous element (greedy).

One or more (greedy).

Zero or one (greedy). Also makes previous quantifier lazy.

Exactly n times.

n or more times.

Between n and m times (inclusive).

Zero or more, lazy (as few as possible).

One or more, lazy.

Zero or one, lazy.

Lazy range — match as few as possible within range.

Capturing group — remembers the match.

Non-capturing group — for grouping without remembering.

Named capturing group.

Positive lookahead — assert what follows.

Negative lookahead — assert what does NOT follow.

Positive lookbehind — assert what precedes.

Negative lookbehind — assert what does NOT precede.

Alternation — match a OR b.

Atomic group (PCRE, .NET — not native JS).

Global — find all matches, not just the first.

Case-insensitive matching.

Multiline — ^ and $ match line breaks.

Dotall — . matches newlines too.

Unicode mode — enables \p{} and proper surrogate handling.

Sticky — match at lastIndex only, no skipping.

Indices — include match start/end positions in result.

Reference to the Nth capturing group.

Reference to a named group.

Backreferences in replacement strings.

The entire match (replacement string).

Text before the match (replacement string).

Text after the match (replacement string).

Lookahead — must be followed by the pattern (zero-width).

Negative lookahead — must NOT be followed by the pattern.

Lookbehind — must be preceded by the pattern.

Negative lookbehind — must NOT be preceded.

Simple email validator (good enough for most cases).

Match an HTTP or HTTPS URL.

ISO date YYYY-MM-DD (format check only).

IPv4 address (format check).

Hex color (3 or 6 digits, optional #).

Collapse runs of whitespace.

Trim leading and trailing whitespace.