The pocket regex cheat sheet (bookmark this)

Every regex token you actually need on one page. Print, bookmark, or pin to your editor.

Anchors

^      start of string (or line with /m)
$      end of string (or line with /m)
\b     word boundary
\B     not a word boundary

Character classes

.      any char (not newline)
[abc]  a, b, or c
[^abc] not a, b, or c
[a-z]  range a through z
\d     digit [0-9]
\D     non-digit
\w     word char [A-Za-z0-9_]
\W     non-word char
\s     whitespace
\S     non-whitespace

Quantifiers

*      0 or more
+      1 or more
?      0 or 1
{n}    exactly n
{n,}   n or more
{n,m}  n to m
*?     lazy version (smallest match)
+?     lazy version

Groups

(abc)        capture group
(?:abc)      non-capturing group
(?<name>abc) named group
\1           back-reference to group 1
\k<name>     named back-reference

Lookarounds

(?=...)      positive lookahead (followed by)
(?!...)      negative lookahead (NOT followed by)
(?<=...)     positive lookbehind (preceded by)
(?<!...)     negative lookbehind (NOT preceded by)

Flags

g    global (find all matches)
i    case-insensitive
m    multiline (^ $ at line boundaries)
s    dotall (. matches newlines)
u    unicode (JS)
x    verbose mode (most flavors, not JS)

Replacement metacharacters

$&   the entire match
$1   capture group 1
$<name>  named group
$$   literal dollar sign

Escape these to use literally

. * + ? ^ $ | ( ) [ ] { } \

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