Table of Contents

Appendix B. Regular Expression Quick Reference Guide

Anchors

^

Start of string, or start of line in multi-line pattern

$

End of string, or end of line in multi-line pattern

\b

Word boundary

\B

Not word boundary


Character Classes

\s

White space

\S

Not white space

\d

Digit

\D

Not digit

\w

Word

\W

Not Word

\x

Hexadecimal digit

Used for matching hex code characters, such as:

  • "\xA9", as in "0xA9", for the copyright symbol

  • "\x5B", as in "0x5B", for the open square bracket


Quantifiers

*

White space

+

Not white space

?

Digit

{3}

Exactly 3

{3,}

3 or more

{3,5}

3, 4, or 5


Escape Sequences

\

Escape following character

^ [ . $ { * ( \ + ) | ? < >


Special Characters

\n

New line

\r

Carriage return

\t

Tab


Groups and Ranges

.

Any character except new line (\n)

\r

Carriage return

(a|b)

a or b

(...)

Group

(?:...)

Passive (non-c­apt­uring) group

[abc]

Range (a or b or c)

[^abc]

Not (a or b or c)

[a-q]

Lower case letter from a to q

[A-Q]

Upper case letter from A to Q

[0-7]

Digit from 0 to 7


String Replacement

$n

nth 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