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Using JavaScript regular expressions

A JavaScript regular expression begins and ends with a forward slash (/). The characters or character combinations explained in Table 1 have special meaning in a Javascript regular expression.

Table 1. Javascript characters

Characters Meaning
\ The escape character - the following character is to be treated as a literal character.
[...] Matches any one character between the brackets. A range of characters can be indicated by a hyphen; for example, /[a-f]/ matches any character between a and f inclusive.
[^...] Matches any one character not between the brackets.
. Matches any character.


\w Matches any word character - equivalent to [a-zA-Z0-9].
\W Matches any nonword character - equivalent to [^a-zA-Z0-9]. The user preference to use case-sensitive matching must be set for this to work.
\d Matches any digit - equivalent to [0-9].
\D Matches any character other than a digit - equivalent to [^0-9]. The user preference to use case-sensitive matching must be set for this to work.
? Matches zero or one occurrence of the previous item.
+ Matches one or more occurrences of the previous item.
* Matches zero or more occurrences of the previous item.
{n,m} Matches the previous item at least n times but no more than m times.
{n} Matches the previous item exactly n times.

A full description of JavaScript regular expressions can be found in JavaScript: The Definitive Guide, published by O'Reilly and Associates.