Steps to reproduce the problem: 1. Paste `const a = {def\u0061ult: 12}` into interpreter What is the expected behavior? No errors, `a` is an object with a member named `default` with value `12`. What went wrong? `Uncaught SyntaxError: Keyword must not contain escaped characters` Relevant spec section: https://tc39.es/ecma262/#prod-IdentifierName This works in chakra-based edge and firefox, however chrome exhibits the same [bug](https://bugs.chromium.org/p/chromium/issues/detail?id=993000&can=2&q=unicode%20escape). I happened to find this while working on https://github.com/microsoft/TypeScript/pull/32718.
Apologies, the error in JSC isn't the one listed above, but rather `SyntaxError: Unexpected escaped characters in keyword token: 'def\u0061ult'`.
Relevant test262 issue, since there doesn't seem to be a test covering it yet: https://github.com/tc39/test262/issues/2285
<rdar://problem/54277270>
(In reply to Wesley Wigham from comment #2) > Relevant test262 issue, since there doesn't seem to be a test covering it > yet: https://github.com/tc39/test262/issues/2285 Thank you Wesley for discovering this and filing the issues. It's so great there so many projects contributing back to test262! Yusuke fixed this in r270481. *** This bug has been marked as a duplicate of bug 219575 ***