RegExp Object
A regular expression is an object that describes a pattern of characters.
Regular expressions are used to perform pattern-matching and "search-and-replace" functions on text.
Modifiers are used to perform case-insensitive and global searches:
| Modifier | Description |
|
i |
Perform case-insensitive matching |
|
g
|
Perform a global match (find all matches rather than stopping after the first match) |
|
m
|
Perform multiline matching |
Brackets
Brackets are used to find a range of characters:
| Expression | Description |
|
[abc]
|
Find any character between the brackets |
|
[^abc]
|
Find any character NOT between the brackets |
|
[0-9]
|
Find any character between the brackets (any digit) |
|
[^0-9]
|
Find any character NOT between the brackets (any non-digit) |
|
(x|y)
|
Find any of the alternatives specified |
Metacharacters
Metacharacters are characters with a special meaning:
|
Metacharacter |
Description |
|
. |
Find a single character, except newline or line terminator |
|
\w |
Find a word character |
|
\W |
Find a non-word character |
|
\d |
Find a digit |
|
\D |
Find a non-digit character |
|
\s |
Find a whitespace character |
|
\S |
Find a non-whitespace character |
|
\b |
Find a match at the beginning/end of a word |
|
\B |
Find a match not at the beginning/end of a word |
|
\0 |
Find a NUL character |
|
\n |
Find a new line character |
|
\f |
Find a form feed character |
|
\r |
Find a carriage return character |
|
\t |
Find a tab character |
|
\v |
Find a vertical tab character |
|
\xxx |
Find the character specified by an octal number xxx |
|
\xdd |
Find the character specified by a hexadecimal number dd |
|
\uxxxx |
Find the Unicode character specified by a hexadecimal number xxxx |
Quantifiers
|
Quantifier |
Description |
|
n+ |
Matches any string that contains at least one n |
|
n* |
Matches any string that contains zero or more occurrences of n |
|
n? |
Matches any string that contains zero or one occurrences of n |
|
n{X} |
Matches any string that contains a sequence of X n's |
|
n{X,Y} |
Matches any string that contains a sequence of X to Y n's |
|
n{X,} |
Matches any string that contains a sequence of at least X n's |
|
n$ |
Matches any string with n at the end of it |
|
^n |
Matches any string with n at the beginning of it |
|
?=n |
Matches any string that is followed by a specific string n |
|
?!n |
Matches any string that is not followed by a specific string n |