Regular Expressions in JavaScript

Regular Expressions In JavaScript

Regular Expressions In JavaScript

Basic:

Regular Expressions In JavaScript

Basic:

Anchors

^ Start of string or line
\A Start of string
$ End of string or line
\Z End of string
\b Word boundary
\B Not word boundary
\< Start of word
\> End of word

Character Classes

\c Control character
\s Whitespace [ \t\r\n\v\f]
\S Not Whitespace [^ \t\r\n\v\f]
\d Digit [0–9]
\D Not digit [⁰-9]
\w Word [A-Za-z0–9_]
\W Not Word [^A-Za-z0–9_]
\x Hexadecimal digit [A-Fa-f0–9]
\O Octal Digit [0–7]

POSIX Classes

[:upper:] Uppercase letters [A-Z]
[:lower:] Lowercase letters [a-z]
[:alpha:] All letters [A-Za-z]
[:alnum:] Digits and letters [A-Za-z0–9]
[:digit:] Digits [0–9]
[:xdigit:] Hexadecimal digits [0–9a-f]
[:punct:] Punctuation
[:blank:] Space and tab [ \t]
[:space:] Blank characters [ \t\r\n\v\f]
[:cntrl:] Control characters [\x00-\x1F\x7F]
[:graph:] Printed characters [\x21-\x7E]
[:print:] Printed characters and spaces [\x20-\x7E]
[:word:] Digits, letters and underscore [A-Za-z0–9_]

Pattern Modifiers

//g Global Match (all occurrences)
//i Case-insensitive
//m Multiple line
//s Treat string as single line
//x Allow comments and whitespace
//e Evaluate replacement
//U Ungreedy pattern

Escape Sequences

\ Escape following character
\Q Begin literal sequence
\E End literal sequence

Quantifiers

* 0 or more
+ 1 or more
? 0 or 1 (optional)
{3} Exactly 3
{3,} 3 or more
{2,5} 2, 3, 4 or 5

Groups and Ranges

. Any character except newline (\n)
(a|b) a or b
(…) Group
(?:…) Passive (non-capturing) group
[abc] Single character (a or b or c)
[^abc] Single character (not a or b or c)
[a-q] Single character range (a or b … or q)
[A-Z] Single character range (A or B … or Z)
[0–9] Single digit from 0 to 9

Assertions

?= Lookahead assertion
?! Negative lookahead
?<= Lookbehind assertion
?!= / ?<! Negative lookbehind
?> Once-only Subexpression
?() Condition [if then]
?()| Condition [if then else]
?# Comment

Special Characters

\n New line
\r Carriage return
\t Tab
\v Vertical tab
\f Form feed
\ooo Octal character ooo
\xhh Hex character hh

String Replacement

$n n-th non-passive group
\(2 “xyz” in /^(abc(xyz))\)/
\(1 “xyz” in /^(?:abc)(xyz)\)/
$` Before matched string
$’ After matched string
$+ Last matched string
$& Entire matched string

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