WPT details: Covered by test262: https://github.com/tc39/test262/tree/main/test/built-ins/RegExp/unicodeSets/generated
Add set operations, string literals, nested classes and unicode properties of strings to regular expression character classes. Set operations and unicode properties of strings allow developers to create regular expressions matching strings with certain unicode characters with ease. E.g. /[\p{Script_Extensions=Greek}&&\p{Letter}]/v matches all greek letters.