Modifiers
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 digit from 0 to 9 |
[A-Z] |
Find any character from uppercase A to uppercase Z |
[a-z] |
Find any character from lowercase a to lowercase z |
[A-z] |
Find any character from uppercase A to lowercase z |
[adgk] |
Find any character in the given set |
[^adgk] |
Find any character outside the given set |
(red|blue|green) |
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 |
RegExp Object Properties
Property |
Description |
global |
Specifies if the "g" modifier is set |
ignoreCase |
Specifies if the "i" modifier is set |
lastIndex |
The index at which to start the next match |
multiline |
Specifies if the "m" modifier is set |
source |
The text of the RegExp pattern |
RegExp Object Methods
Method |
Description |
compile() |
Compiles a regular expression |
exec() |
Tests for a match in a string. Returns the first match |
test() |
Tests for a match in a string. Returns true or
false |
Examplevar patt=new RegExp(pattern,modifiers);
or
var patt=/pattern/modifiers;
Global search for 'is' <html>
<body>
<script type="text/javascript">
var str="Is this all there is?";
var patt1=/is/g;
document.write(str.match(patt1));
</script>
</body>
</html>
test()
The test() method searches a string for a specified value, and returns true
or false, depending on the result. <html>
<body>
<script type="text/javascript">
var patt1=new RegExp("e");
document.write(patt1.test("The best things in life are free"));
</script>
</body>
</html>
exec()
The exec() method searches a string for a specified value, and
returns the text of the found value. If no match is found, it returns null. <html>
<body>
<script type="text/javascript">
var patt1=new RegExp("e");
document.write(patt1.exec("The best things in life are free"));
</script>
</body>
</html>
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