1388831 - Object Inspector should show [[ProxyHandler]] and [[ProxyTarget]] instead of executing proxy traps

Status: RESOLVED WORKSFORME

(DevTools :: Console, defect)

Description

[Oriol Brufau [:Oriol]]

When you use the Object Inspector on a proxy object, it attempts to get the own properties.

It should display the [[ProxyTarget]] and [[ProxyHandler]] instead.

https://dxr.mozilla.org/mozilla-central/rev/a921bfb8a2cf3db4d9edebe9b35799a3f9d035da/devtools/server/actors/object.js#275-276

    names = this.obj.getOwnPropertyNames();     //  <-- ownKeys trap
    symbols = this.obj.getOwnPropertySymbols(); //  <-- ownKeys trap

https://dxr.mozilla.org/mozilla-central/rev/a921bfb8a2cf3db4d9edebe9b35799a3f9d035da/devtools/server/actors/object.js#298

    prototype: this.hooks.createValueGrip(this.obj.proto), //  <-- getPrototypeOf trap

Comment 1

[Nicolas Chevobbe [:nchevobbe]]

Hello Oriol, thanks for reporting this.
I filed https://github.com/devtools-html/devtools-core/issues/583 for doing this work on the reps side.

Comment 2

[Nicolas Chevobbe [:nchevobbe]]

Can you confirm it works as expected Oriol ?

Comment 3

[Oriol Brufau [:Oriol]]

It seems there is still a getPrototypeOf call. __proto__ should not be shown.

    inspect(new Proxy({},{}))

    ▼ Proxy
      ▶ <target>: Object {  }
      ▶ <handler>: Object {  }
      ▶ __proto__: Proxy { … }

Comment 4

[Oriol Brufau [:Oriol]]

Anyways, onPrototypeAndProperties attempts to access objects that shouldn't be accessed (not only proxies). Probably this will be fixed in 1394559, then it would make sense to also modify onPrototype to just return null.

Comment 5

[Nicolas Chevobbe [:nchevobbe]]

We don't call onPrototypeAndProperties anymore :)
Here is the function where we decide whether or not to load the prototype of a given node : https://github.com/devtools-html/devtools-core/blob/b9616604b90565680292f4ff3bfe2565ad415b17/packages/devtools-reps/src/object-inspector/utils/node.js#L809 .
Here, if we don't need to load it for Proxy, we could probably add another case `&& !nodeIsProxy(item)`.

Comment 6

[Nicolas Chevobbe [:nchevobbe]]

Let's file an issue on devtools-core to not load prototype for Proxies