On Tue, Jan 8, 2013 at 12:40 PM, Andrea Giammarchi <[email protected]> wrote: > So, I am playing with FF 18 and I have this behavior: > > var a = new Proxy([], {}); > console.log(a instanceof Array); // true > console.log(Array.isArray(a)); // true > console.log({}.toString.call(a));// [object Array] > > Function.apply(null, a); // anonymous() > > Cool uh? there's no way to tell that a is not actually an array but rather a > proxy: awesome!!! > > Now I go in that dark place called DOM: > > var n = new Proxy(document.createElement("p"), {}); > console.log(n instanceof HTMLElement);// true > console.log({}.toString.call(n)); // true > document.body.appendChild(n); > // Error: Could not convert JavaScript argument arg 0 > [nsIDOMHTMLBodyElement.appendChild] > > Is this meant? 'cause it looks lik ewe have half power here and once again > inconsistencies ... thanks for explaining me this.
As Francois points out, this is a known problem. DOM objects don't live solely in JS - they tend to have C++ backing classes that do a lot of the heavy lifting. Your average JS object, without such C++ support, simply won't work with the JS methods that, when they call back into C++, expect to see the DOM C++ classes. This is a problem elsewhere, too - Web Components really wants to make it easy to subclass DOM objects, but we've had to twist ourselves into knots to do it in a way that alerts the C++ side "early enough" that it can create the new objects with appropriate backing C++ classes. It can potentially be solved by efforts like moving the DOM into JS, which browsers are pursuing to various degrees, but it's a hard problem on the impl side. Meanwhile, there is unforgeable magic behind DOM objects, and nothing we can really do about it. ~TJ _______________________________________________ es-discuss mailing list [email protected] https://mail.mozilla.org/listinfo/es-discuss
