The complete RegEx Cheat Sheet
by doublehelix via cheatography.com/27391/cs/7932/
Anchors (bound๎aries)
^ Start of string or line
$ End of string or line
\A Start of input (ignores 'm' flag)
\Z End of input (ignores 'm' flag)
\G End of the previous match
\b Word bo undary (any position proceeded or followed - but not both -
by a letter, digit or unders๎core)
\B Non-word boundary
Character and Sets
\w Word [a-zA-๎Z0-9_]
\W Non-word [^a-zA๎-Z0-9_]
\d Digit [0-9]
\D Non-digit
\s Whitespace (Form-๎feed, tab, vertic๎al-tab, new
line, carriage return and space)
[\f\t๎\x0b\n\r ]
\S Non-wh๎ite๎space
\x Hexade๎cimal digit \x00=null; \x0d=\r;
[\x61-๎\x7๎a]=๎[a-z]
\O Octal digit
. Any character (except new line \n)
Groups
(...) Capture group - captures a set of characters for a later
expression
(?:...) Non-ca๎pture group - groups an expression but does not capture.
e.g. /((?:f๎oo|๎fu)๎bar)/ matches "๎foo๎bar๎" or "๎fub๎ar" without "๎foo๎" or
"๎fu" appearing as a captured subpattern
(?
=...)
Lookahead - match on the characters following. e.g. /ab(?= c)/
match "๎ab" only when followed by "๎c"
(?!...) Negative lookahead - match on characters that aren't following .
e.g. /ab(?!c)/ match "๎ab" only when NOT followed by "๎c"
(?
<๎=...)
Positive look-b๎ehind assertion. e.g. /(?<=f๎oo)bar/ matches " ๎bar๎"
when preceded by "๎foo๎"
(?
<๎!...)
Negative look-b๎ehind assertion. e.g. /(?<!f๎oo)bar/ - matches "๎bar๎"
when not preceded by "๎foo๎"
(?
#...)
Comment e.g. (?# This comment is ignored entirely)
Unicode character support
\x0000๎-\xFFFF Unicode hexade๎cimal character set
\x00-\xFF ASCII hexade๎cimal character set
\cA-\cZ Control characters
Unicode is not fully supported on all platforms. JavaScript prio r to ES6 for
example allows ASCII hex but not full Unicode hex.
Special Characters
\n New line
\r Carriage return
\t Tab
\v Vertical tab
\f Form feed
Quanti๎fiers
* Zero or more
+ One or more
? Zero or One (i.e. optional)
{n} Exactly 'n' (any number)
{n,} Minimum ('n' or more)
{n,m} Range ('n' or more, but less or equal to 'm')
Flags (expre๎ssion modifiers)
/m Milti-๎line. (Makes ^ and $ match the start and end of a line
respec๎tively)
/s Treat input as a single line. (Makes '.' match new lines as we ll)
/i Case insens๎itive p attern matching.
/g Global matching . (Don't stop after first match in a replac๎ement
function)
/x Extended matching. (disregard white-๎space not explicitly esca ped,
and allow comments starting with #)
Escape Characters
In regular expres๎sions, the following characters have special m eaning and
must be escaped: ^ $ [ { ( ) < > . * \ + | ?
Additi๎onally the hyphen (-) and close square bracket (]) must be escaped
when in an expression set ([...]).
e.g. /\(\d๎{3}\) \d{4}[\- ]\d{4}/ matches "๎(nnn) nnnn-n๎nnn๎" or
"๎(nnn) nnnn nnnn" (where n is a numeric digit).
By doublehelix
cheatography.com/doublehelix/
Published 30th January, 2017.
Last updated 31st January, 2017.
Page 1 of 1.
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