Rule proposal: `prefer-regexp-code-point-escape`

Unicode code point escapes are new in ES6. They support more bits than older escapes and it’s better to always use them for consistency, even when they’re not required.

• https://exploringjs.com/es6/ch_unicode.html#sec_escape-sequences
• https://mathiasbynens.be/notes/javascript-escapes#unicode-code-point

This overlaps with the no-hex-escapes rule. Not sure whether we should deprecate that one. It’s plausible that someone wants to prevent Hex escapes, but not prefer code point escapes. Opinions welcome.

Inspired by https://github.com/eslint/eslint/issues/12488.

Fail

const foo = '\123'; // Octal
const foo = '\cA'; // Control escape sequence
const foo = '\x7A'; // Hex
const foo = '\u2661'; // Unicode escape sequence
const foo = '\uD83D\uDCA9'; // Unicode surrogate pair

Pass

const foo = '\u{7A}';
const foo = '\u{1F4A9}';

[sindresorhus]

And I prefer const foo = ‘\u007A’; over const foo = ‘\u{7A}’;

Did you see my arguments for why \u{7A} is better? It’s shorter and it lets you use the same syntax always.

It also makes escapes stand out more because of the braces, which makes strings with a lot of escapes more readable.

[sindresorhus]

This is now accepted.