Bug 159203 – Use Unicode 9’s `ID_Start` & `ID_Continue` for identifiers

• Status: NEW
• Component: JavaScriptCore

[Mathias Bynens]

* Unicode 8 has 2,518 `ID_Start` symbols; Unicode 9 has 2,669, i.e. 151 more (no removals).
* Unicode 8 has 109,830 `ID_Continue` symbols; Unicode 9 has 117,007, i.e. 7,177 more (no removals).

E.g. these should not throw per Unicode 9:

    Function('var \u{1E943}'); // new ID_Start
    Function('var _\u{1E959}'); // new ID_Continue

I’ve attached `results.js` which contains the full list of new `ID_Start` and `ID_Continue` symbols in Unicode 9, and the Node.js script used to generate it.

[Mathias Bynens]

Created attachment 282228 [details]
Node.js script that outputs lists of new `ID_Start` and `ID_Continue` symbols

[Mathias Bynens]

Created attachment 282229 [details]
results.js

[Mathias Bynens]

Bugzilla won’t allow me to add https://github.com/Microsoft/ChakraCore/issues/1208 to the “See also” list. Can that be fixed?

[Alexey Proskuryakov]

Per <http://www.ecma-international.org/ecma-262/7.0/>, "A conforming implementation of ECMAScript must interpret source text input in conformance with the Unicode Standard, Version 8.0.0 or later and ISO/IEC 10646".

[Mathias Bynens]

The intent is to use the latest available Unicode version. See https://github.com/tc39/ecma262/pull/620 for some discussion.