Hi.
I must admit I didn't follow the whole thread about native element
proxyfication but when I left the consensus was that the native element should
not be proxied (ie: it would not work like Object.create(...) do not work for
them).
I've however a compelling use case that may make some of us rethink the
situation.
Let's say I want to implement a polyfill for MapEvent whose definition is as
follows:
interface MapEvent : Event {
getter any item(DOMString name);
}
In case of no-proxy-for-native-objects, I've no way to do it properly because
implementing 'getter' requires me to use a Proxy but having a functional event
will force me to use a natively-branded element (like
document.createEvent("CustomEvent")) and changes its prototype chain to match
my needs.
So, I would like to reiterate the need for a proxification of native objects:
the proxification would be used in the case of polyfills and it doesn't matter
if it's possible to extract information about the underlying element, the only
goal of the prolyfill is to implement the getter anyway.
To solve the wrapping/unwrapping, the solution I already talked about would be
a good fit:
ProxiedCustomEvent implements CustomEvent
- nativeEvent : CustomEvent
- proxy : ECMAScriptObject
so that if the object has to be returned again later (ie: to a callback) the
unwrapping works as expected.
The other option would be to allow to transform any native object into a proxy
but I heard it wasn't an approach that did get a lot of love. Maybe we should
reconsider it?
ECMAScriptObject
- object nativeBrand
- ...
In this case, the wrapping/unwrapping would work exactly as usual, with the
small difference that the ECMAScript wrapper of the CustomEvent would be a
Proxy. Using symbols, this could be as easy as:
function MapEvent() {
var e = document.createEvent("CustomEvent");
e.initCustomEvent(...);
e[Object.__Prototype__] = MapEvent.prototype;
e[Object.__Get__] = function getter(name) { ... }
e[Object.__Has__] = function has(name) { ... }
...
return e;
}
var e = new MapEvent();
e instanceof MapEvent; // true
document.body.dispatchEvent('map', e); // works
Any thought on this?
François
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