On Nov 12, 2014, at 11:58 AM, Jeremy Martin wrote:
> My opinion is that array testing is fundamental to core JS and is worth the
> exception.
>
> Knowing that Array.isArray() tests fail for proxies, I'd be afraid to ever
> create a Proxy for an array that I don't control the complete lifecycle of.
> That seems to critically inhibit the usefulness of Proxies, especially when
> transparency seems to have been an intended characteristic of them going all
> the way back to the strawman days.
Proxies are not transparent forwarders! In particular their default handling
of the `this` value on method invokes will break any built-in method that needs
to access "internal slots" of an object.
```js
var p = new Proxy(new Array, {});
```
will give you an object that will fail on serval of the Array.prototype methods.
It is even worse for other built-ins such as Map or the typed array
constructors.
Allen
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