Appendix A. JavaScript Regex Cheat Sheet

In this appendix, you can find a summary of the patterns used in regular expressions in JavaScript along with their descriptions, and a list of useful methods to test and create regular expressions.

The following Regex topics will be covered in this appendix:

  • Character classes and literals
  • Character sets
  • Boundaries and quantifiers
  • Grouping, alternation, and back reference
  • Useful methods

Character classes

In the following table, you can find the patterns for character classes, which tell the Regex to match a single character:

Pattern

Description

Example

.

This matches any character, except newline or another unicode line terminator, such as ( , , u2028 or u2029).

/f.o/ matches "fao", "feo", and "foo"

w

This matches any alphanumeric character, including the underscore. It is equivalent to [a-zA-Z0-9_].

/w/ matches "f" in "foo"

W

This matches any single nonword character. It is equivalent to [^a-zA-Z0-9_].

/W/ matches "%"in "100%"

d

This matches any single digit. It is equivalent to [0-9].

/d/ matches "1" in "100"

D

This matches any non digit. It is equivalent to [^0-9].

/D/ matches "R" in "R2-D2"

s

This matches any single space character. It is equivalent to [ vf].

/s/ matches " " in "foo bar"

S

This matches any single nonspace character. It is equivalent to [^ vf].

/S/ matches "foo" in "foo bar"

Literals

In the following table, you can find the patterns for literal characters, which tell the Regex to match a special character:

Pattern

Description

Example

Alphanumeric

These match themselves literally.

/javascript book/ matches "javascript book" in "javascript book"

This matches a NUL character.

 

This matches a newline character.

 

f

This matches a form feed character.

 

This matches a carriage return character.

 

This matches a tab character.

 

v

This matches a vertical tab character.

 

[]

This matches a backspace character.

 

xxx

This matches the ASCII character, expressed by the xxx octal number.

/112/ matches the "J" character

xdd

This matches the ASCII character, expressed by the dd hex number.

/x4A/ matches the "J" character

uxxxx

This matches the ASCII character, expressed by the xxxx UNICODE.

/u0237/ matches the "J" character

This indicates whether the next character is special and is not to be interpreted literally.

/^/ matches "^" in "char ^"

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