regexObscureRanges

Reports obscure character ranges in regular expressions.

✅ This rule is included in the ts logical and logicalStrict presets.

Character ranges like A-z or 0-A span across non-obvious character sets and can lead to unexpected matching behavior. Standard alphanumeric ranges like a-z, A-Z, and 0-9 are preferable. This rule reports obscure character ranges in regular expressions.

Examples

Cross-Case Range

❌ Incorrect

const pattern = /[A-z]/;

✅ Correct

const pattern = /[A-Za-z]/;

The range A-z includes characters like [, \, ], ^, _, and backtick in addition to letters.

Digit to Letter Range

❌ Incorrect

const pattern = /[0-A]/;

✅ Correct

const pattern = /[0-9A]/;

Mixed Escape Sequence Range

❌ Incorrect

const pattern = /[\cA-Z]/;

✅ Correct

const pattern = /[\cA-\cZ]/;

Options

This rule is not configurable.

When Not To Use It

If you intentionally use non-standard character ranges for specific matching needs, or if your codebase has established patterns that rely on these ranges, you might want to disable this rule.

Further Reading

• MDN: Character classes
• MDN: Regular expressions

Equivalents in Other Linters

• ESLint: regexp/no-obscure-range