Question about allowed characters in identifier names

Mathias Bynens mathias at
Thu Sep 5 01:06:38 PDT 2013

On 26 Aug 2013, at 04:08, Norbert Lindenberg <ecmascript at> wrote:

> On Aug 24, 2013, at 23:43 , Mathias Bynens <mathias at> wrote:
>> I would suggest adding something like `String.isIdentifier` which accepts a multi-symbol string or an array of code points to the strawman. Seems useful to be able to do `String.isIdentifier('foobar')`
> What would be the use case(s) for that?

Tools like

> Would it accept only an actual identifier or all possible escaped forms of one (i.e., only "𠮷野家" or also "\u{20BB7}野\u5BB6")?

Both, since `"𠮷野家" === "\u{20BB7}野\u5BB6"`. That string is also equal to `"\uD842\uDFB7\u91CE\u5BB6"` although it hasn’t been decided if that should be a valid identifier too (since it uses the surrogate code points explicitly): <>. That complicates things.

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