regexUnnecessaryCharacterClasses

Reports character classes that wrap a single element that does not require brackets.

✅ This rule is included in the ts logical presets.

Reports character classes that wrap a single element that does not require brackets. A character class like [a] or [\d] can be simplified to just a or \d.

Examples

Single Character Class

A character class with a single character can be unwrapped.

❌ Incorrect

const pattern = /[a]/;

✅ Correct

const pattern = /a/;

Escape Sequence Class

A character class with a single escape sequence can be unwrapped.

❌ Incorrect

const pattern = /[\d]/;

✅ Correct

const pattern = /\d/;

RegExp Constructor

The rule also checks regex patterns in RegExp constructor calls.

❌ Incorrect

const pattern = new RegExp("[a]");

✅ Correct

const pattern = new RegExp("a");

Valid Cases

These cases are valid and will not be reported:

// Negated classes
const negated = /[^a]/;

// Backspace escape (has special meaning in character class)
const backspace = /[\b]/;

// Multiple elements
const multiple = /[ab]/;

// Character ranges
const range = /[a-z]/;

// Equals sign (commonly used in regex for readability)
const equals = /[=]/;

Options

This rule is not configurable.

When Not To Use It

If you prefer to use character classes for consistency or readability, even when they contain only a single element, you might prefer to disable this rule.

Further Reading

• MDN: Character classes

Equivalents in Other Linters

• ESLint: regexp/no-useless-character-class