Finiteness of object properties set

Lasse Reichstein reichsteinatwork at
Wed Sep 7 06:29:02 PDT 2011

On Wed, Sep 7, 2011 at 2:07 PM, David Bruant <david.bruant at> wrote:

> If this is really considered, the problem to solve is to express an
> infinite set with a finite representation. RegExps may be a solution. One
> big question is on RegExp expressivity: Can any infinite string set be
> expressed with (a finite number of) JS RegExps?

Nope. Any finite set of RegExps can be combined into a single RegExp, so the
language they recognize is still regular (or what the class of languages
recognized by JS RegExps really is, since it's bigger than the regular
languages, but doesn't include all context free langauges).

As for proxies with arbitrarily many properties, I don't think there's a way
to prevent it (it's the catch-all effect).
The problem is for the proxy creator to decide what to return for keys().
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