Regex Playground

Pattern

.

Any character except a line break; use s to include them.

^   $

Start and end; use m for line boundaries.

\d   \w   \s

Digit, word character, whitespace.

[abc]   [^abc]

Included or excluded characters.

*   +   ?

Zero or more, one or more, optional.

{n,m}

Between n and m repetitions.

(…)   (?:…)

Capturing or non-capturing group.

(?<name>…)

Named capture group.

(?=…)   (?!…)

Positive or negative lookahead.

\p{L}

Unicode letter; requires u or v.

Replacement

$$

A literal dollar sign.

$&

The entire match.

$1 … $99

A numbered capture group.

$<name>

A named capture group.

$`   $'

The text before or after the match.

Ranges use UTF-16 offsets. The end position is exclusive. A narrow line in the test text marks an empty match.

g replaces every match; without g, only the first match is replaced. Sticky matching starts at position 0.