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Character Classes are characters enclosed in square brackets [] .

A character class matches any character from a set within brackets:

// Match Digits
const pattern = /[0-9]/;

JavaScript Regex Character Classes

Class	Description
[a]	Matches the character between the brackets
[^a]	Matches all characters NOT between the brackets
[abc]	Matches all characters between the brackets
[^abc]	Matches all characters NOT between the brackets
[a-z]	Matches all characters in the range from a to z
[^a-z]	Matches all characters NOT in the range from a to z
[0-9]	Matches all characters in the range from 0 to 9

Example [HW]

let text = "Hello World!";
const pattern = /[HW]/g;
let result = text.match(pattern);

Example [A-Z]

let text = "This is W3School";
const pattern = /[A-Z]/g;
let result = text.match(pattern);

Example [1234]

let text = "123456789";
const pattern = /[1234]/g;
let result = text.match(pattern);

Example [1-4]

let text = "123456789";
const pattern = /[1-4]/g;
let result = text.match(pattern);

[01234] is the same as [0-4]

[abcde] is the same as [a-e]

Regular Expression Search and Replace can be done with different methods.

Method	Description
match( regex )	Returns an Array of results
matchAll( regex )	Returns an Iterator of results
replace( regex )	Returns a new String
replaceAll( regex )	Returns a new String
search( regex )	Returns the index of the first match
split( regex )	Returns an Array of results

Method	Description
regex .exec()	Returns an Iterator of results
regex .test()	Returns true or false