Appendix B. Regular Expression Quick Reference Guide



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


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


Word boundary


Not word boundary

Character Classes


White space


Not white space




Not digit




Not Word


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



White space


Not white space




Exactly 3


3 or more


3, 4, or 5

Escape Sequences


Escape following character

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

Special Characters


New line


Carriage return



Groups and Ranges


Any character except new line (\n)


Carriage return


a or b




Passive (non-c­apt­uring) group


Range (a or b or c)


Not (a or b or c)


Lower case letter from a to q


Upper case letter from A to Q


Digit from 0 to 7

String Replacement


nth non-passive group


"xyz" in /^(abc(xyz))$/


"xyz" in /^(?:abc)(xyz)$/


Before matched string


After matched string


Last matched string


Entire matched string