Proxy to Array fools most methods of checking whether Array is Array about harmony-reflect HOT 11 OPEN

Regarding the JSON.stringify, a workaround is to do this:

  var proxy = new Proxy(obj, {
    get: function(target, property, receiver) {
      if (property === 'toJSON') {
        return () => target;
      }
 });

from harmony-reflect.

I just checked these issues against the most recent version of v8 (3.17.16.2). Issue 1 from above (JSON.stringify dying on proxies) is fixed. Issue 3 from above (Arrays returning "object Object") is still there, as the following d8 console session shows:

V8 version 3.17.16.2 [console: readline]
d8> load("/home/parallels/git/experiments/node_modules/harmony-reflect/reflect.js");
undefined
d8> a = ["a","b","c"];
["a", "b", "c"]
d8> Object.prototype.toString.apply(a);
"[object Array]"
d8> var p = Proxy(a, {});
undefined
d8> print(p);
a,b,c
undefined
d8> print(a);
a,b,c
undefined
d8> Object.prototype.toString.apply(p);
"[object Object]"

from harmony-reflect.

Thanks for clarifying. I'd meant to report these results using that same Node version but had invoked the wrong one. Whoops.

I see the same thing as @billmark, which is nice because the JSON.stringify issue I complained about as (1) above actually is fixed, but now that it works, it turns out that it, just like JSON2.stringify and util.inspect, does not think that proxy-to-array is an array.

So scratch complaint (1), but (2) and (3) turn out to be even truer than I thought.

from harmony-reflect.

More details: I also checked against the slightly more recent "bleeding_edge" version of v8, "3.18.0 (candidate)", and it still has the issue that calling Object.prototype.toString on a proxied array returns "[object Object]" rather than "[object Array]".

from harmony-reflect.

I just committed a patch so that Array.isArray and Object.prototype.toString automatically unwrap proxies. Those methods now return the expected result on proxies for arrays:

var p = Proxy([] , {});
Object.prototype.toString.call(p) // [object Array]
Array.isArray(p) // true

However, JSON.stringify still serializes proxies-for-arrays as objects. This is because that algorithm internally uses its own isArray check, which my library cannot intercept. AFAICT, this is something that can be solved only by proxies directly provided by the engine. The alternative is to re-implement JSON.stringify in JavaScript itself, which doesn't seem to be a good alternative.

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Thanks, Tom.

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Has any of this made it's way to the npm module?

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Not yet. Thanks for bringing it to my attention. I'll upload a new npm package shortly.

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npm module v0.0.5 now contains the patches to Array.isArray and Object.prototype.toString to unwrap proxies.

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Thanks, Tom!

from harmony-reflect.

Thanks!

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