dhtmlkitchen at gmail.com
Wed Oct 10 18:01:36 PDT 2007
On 10/10/07, Brendan Eich <brendan at mozilla.org> wrote:
> On Oct 10, 2007, at 3:53 PM, Garrett Smith wrote:
> > Typechecking is a problem.
> > typeof is limited and allows host objects to return anything. The
> > problem is that some host objects return "function", for example, a
> > NodeList in Safari. This is perfectly legal, according to the spec.
> See http://bugs.ecmascript.org/ticket/153 -- for a general, universal
> is-it-callable test, you would write
> if (it is Callable) ...
> > How is type checking addressed in ES4?
> The |is| operator tests universal or Platonic type, which involves
> shared, immutable type descriptors that do not vary across windows or
> frames. So
> if (a is Array) ...
> will work no matter where a was constructed.
Immutable type descriptor. I like it!
Programming is a collaborative art.
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