escapeSequenceCasing

Reports escape sequences with lowercase hexadecimal characters.

✅ This rule is included in the ts stylisticStrict presets.

Enforces a consistent escaped value style by requiring escape sequence values to use uppercase hexadecimal characters. Uppercase characters promote readability by making the escaped value more distinguishable from the identifier.

Examples

Hexadecimal Escape Sequences

❌ Incorrect

const foo = "\xa9";

✅ Correct

const foo = "\xA9";

Unicode Escape Sequences

❌ Incorrect

const foo = "\ud834";

✅ Correct

const foo = "\uD834";

Unicode Code Point Escape Sequences

❌ Incorrect

const foo = "\u{1d306}";

✅ Correct

const foo = "\u{1D306}";

Control Character Escape Sequences

❌ Incorrect

const foo = "\ca";

✅ Correct

const foo = "\cA";

Options

This rule is not configurable.

When Not To Use It

If your codebase has an established convention of using lowercase escape sequences, or if you don’t care about the casing of escape sequences, you may disable this rule.

Further Reading

• MDN: Escape sequences

Equivalents in Other Linters

• ESLint: unicorn/escape-case
• Oxlint: unicorn/escape-case