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Combination classes

Range classes work whenever the characters you want to test are in order by character code. Consider

the following example:

var sToMatch = “num1, num2, num3, num4, num5, num6, num7, num8, num9”;

var reOneToFour = /num[1-4]/gi;

var arrMatches = sToMatch.match(reOneToFour);

After execution,

arrMatches

contains four items:

“num1”

“num2”

“num3”

, and

“num4”

because they

all match

num

and are followed by a character in the range

1 through 4

Combination classes

combination class

is a character class that is made up of several other character classes. For instance,

suppose you want to match all letters

through

, numbers

through

, and the new line character.

The class looks like this:

[a-m1-4\n]

Note that there are no spaces between the different internal classes.

Predefined classes

Because some patterns are used over and over again, a set of predefined character classes is used to

make it easy for you to specify some complex classes. The following table lists all the predefined classes:

Code Equal To

Matches

[^\n\r]

Any character except new line and carriage return

[0-9]

A digit

[^0-9]

A non-digit

[ \t\n\x0B\f\r]

A white-space character

JavaScript/ECMAScript doesn’t support union and intersection classes as do other

regular expression implementations. This means you can’t make patterns such as

[a-m[p-z]]

[a-m[^b-e]]

You can also negate range classes so as to exclude all characters within a given range.

For example, to exclude characters 1 through 4, the class is

[^1-4]

Note that

[a-z]

matches only lowercase letters unless the regular expression is set

to case insensitive by using the i option. To match only uppercase letters, you must

use

[A-Z]

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