Valid JavaScript variable names in ECMAScript 6 · Mathias Bynens

ES2015 updates the grammar for identifiers. This affects a number of things, but most importantly, identifiers can be used as variable names, and identifier names are valid unquoted property names. This post describes the observable changes compared to the old ES5 behavior. Reserved words ES2015 reserves the await keyword in module contexts for use in the future. // Valid in ES5, but invalid in an

[hogashi]

“var \u0061;” / "The rest of the identifier can contain $, _, U+200C zero width non-joiner, U+200D zero width joiner, or any symbol with the Unicode derived core property ID_Continue."

[ginpei]

ES6で使えなくなる変数名の話。まあ基本的には普通の名前なら問題ない。

[efcl]

ES5と6でidentifierに使える文字列やエスケープシーケンスなどについて

[teramako]

Identifierに使えるUnicode表現とか