Name: JavaScript Regular Expressions: Character Classes
Description: Character classes let you match sets of characters using square brackets.

Character classes let you match sets of characters using square brackets. This lesson covers the fundamentals: listing specific characters, negating with a caret (^), defining ranges like a-z or 0-9, and combining multiple ranges. You’ll learn how to build flexible patterns that match any character from a defined set — whether it’s letters, digits, or a mix.

app.js

import output from "./output.js";

const str = `cat mat bat Hat ?at 0at`;
// Character classes in regular expressions allow
// us to identify specific sets of characters
// that we're willing to accept as part of
// our matches
let regex = /at/g;
regex = /.at/g;
regex = /[bc]at/g;
regex = /[cb]at/g;
regex = /[^cb]at/g;
// character class ranges
regex = /[a-z]at/g;
// union character class ranges
regex = /[a-zA-Z]at/g;
// union character class partial ranges
regex = /[a-dA-Z]at/g;
// negate character classes
regex = /[^a-zA-Z]at/g;
// digits
regex = /[a-zA-Z0-9]at/g;
// union the ? char
regex = /[a-zA-Z0-9?]at/g;

output(str, regex);