1. Regular-expression literal characters Character Matches
Alphanumeric character Itself
The NUL character (u0000)
t Tab (u0009)
n Newline (u000A)
v Vertical tab (u000B)
f Form feed (u000C)
r Carriage return (u000D)
xnn The Latin character specified by the hexadecimal number nn; for example, x0A is the same as n
uxxxx The Unicode character specified by the hexadecimal number xxxx; for example, u0009 is the same as t
cX The control character ^X; for example, cJ is equivalent to the newline character n
2. Regular expression character classes Character Matches
[...] Any one character between the brackets.
[^...] Any one character not between the brackets.
. Any character except newline or another Unicode line terminator.
w Any ASCII word character. Equivalent to [a-zA-Z0-9_].
W Any character that is not an ASCII word character. Equivalent to [^a-zA-Z0-9_].
s Any Unicode whitespace character.
S Any character that is not Unicode whitespace. Note that w and S are not the same thing.
d Any ASCII digit. Equivalent to [0-9].
D Any character other than an ASCII digit. Equivalent to [^0-9].
[b] A literal backspace (special case).
3. Regular expression repetition characters Character Meaning
{n,m} Match the previous item at least n times but no more than m times.
{n,} Match the previous item n or more times.
{n} Match exactly n occurrences of the previous item.
? Match zero or one occurrences of the previous item. That is, the previous item is optional. Equivalent to {0,1}.
+ Match one or more occurrences of the previous item. Equivalent to {1,}.
* Match zero or more occurrences of the previous item. Equivalent to {0,}.
4。 Regular expression alternation, grouping, and reference characters Character Meaning
| Alternation. Match either the subexpression to the left or the subexpression to the right.
(...) Grouping. Group items into a single unit that can be used with *, +, ?, |, and so on. Also remember the characters that match this group for use with later references.
(?:...) Grouping only. Group items into a single unit, but do not remember the characters that match this group.
n Match the same characters that were matched when group number n was first matched. Groups are subexpressions within (possibly nested) parentheses. Group numbers are assigned by counting left parentheses from left to right. Groups formed with (?: are not numbered.
5. Regular-expression anchor characters Character Meaning
^ Match the beginning of the string and, in multiline searches, the beginning of a line.
$ Match the end of the string and, in multiline searches, the end of a line.
b Match a word boundary. That is, match the position between a w character and a W character or between a w character and the beginning or end of a string. (Note, however, that [b] matches backspace.)
B Match a position that is not a word boundary.
(?=p) A positive lookahead assertion. Require that the following characters match the pattern p, but do not include those characters in the match.
(?!p) A negative lookahead assertion. Require that the following characters do not match the pattern p.
6. Regular-expression flags Character Meaning
i Perform case-insensitive matching.
g Perform a global matchthat is, find all matches rather than stopping after the first match.
m Multiline mode. ^ matches beginning of line or beginning of string, and $ matches end of line or end of string.
string.replace(regexp, replacement)
Characters Replacement
$1, $2, ..., $99 The text that matched the 1st through 99th parenthesized subexpression within regexp
$& The substring that matched regexp
$' The text to the left of the matched substring
$' The text to the right of the matched substring
$$ A literal dollar sign
name.replace(/(w+)s*,s*(w+)/, "$2 $1");
text.replace(/"([^"]*)"/g, "''$1''");
text.replace(/bw+b/g, function(word) {
return word.substring(0,1).toUpperCase( ) +
word.substring(1);
});