regexRepeatQuantifiers

Reports consecutive identical elements in regular expressions that should use quantifiers.

✅ This rule is included in the ts stylistic presets.

Matching multiple consecutive characters in a regular expression can be done either by writing out that character repeatedly or using a quantifier. Quantifiers keep the regex shorter and harder to miscount, and they make it obvious how many times a part repeats without visually scanning a long run of characters. For example, writing a{5} is more concise and readable than aaaaa.

This rule reports runs of five or more identical elements in regular expressions and suggests replacing them with quantifiers.

Examples

Repeated Characters

❌ Incorrect

const pattern = /aaaaa/;

✅ Correct

const pattern = /a{5}/;

Escape Sequences

❌ Incorrect

const pattern = /\d\d\d\d\d/;

✅ Correct

const pattern = /\d{5}/;

Character Classes

❌ Incorrect

const pattern = /[a-z][a-z][a-z][a-z][a-z]/;

✅ Correct

const pattern = /[a-z]{5}/;

Dots

❌ Incorrect

const pattern = /...../;

✅ Correct

const pattern = /.{5}/;

RegExp Constructor

❌ Incorrect

const pattern = new RegExp("aaaaa");

✅ Correct

const pattern = new RegExp("a{5}");

Options

This rule is not configurable.

When Not To Use It

If your project has a style guide that prefers explicit repetition for clarity, or if you are programmatically generating regular expressions where repetition is easier to produce, you might want to disable this rule.

Further Reading

• MDN: Quantifier
• MDN: Regular expressions

Equivalents in Other Linters

• ESLint: regexp/prefer-quantifier