fix(reactivity): fix track hasOwnProperty

[edison1105]

close #2619

[skirtles-code]

Correct me if I'm wrong but doesn't this fix assume that hasOwnProperty is being read off the reactive object itself?

If someone did something equivalent to this:

Object.prototype.hasOwnProperty.call(obj, 'a')

then the reactivity still wouldn't be tracked?

While it's unlikely that someone would do that directly in a template, it's pretty common for libraries to do something like this internally (like Vue's hasOwn helper).

[edison1105]

Object.prototype.hasOwnProperty.call(obj, 'a')

This will not be tracked and I am not sure that this PR is the best solution.

[LinusBorg]

Can you add a test?

[edison1105]

Can you add a test?

Done.

[HcySunYang]

According to these specs:

• https://tc39.es/ecma262/#sec-object.prototype.hasownproperty
• https://tc39.es/ecma262/#sec-hasownproperty

1. Assert: Type(O) is Object.
2. Assert: IsPropertyKey(P) is true.
3. Let desc be ? O.[[GetOwnProperty]](P).
4. If desc is undefined, return false.
5. Return true.

In step 3 O.[[GetOwnProperty]](P), which can be traped by getOwnPropertyDescriptor, something like this:

function getOwnPropertyDescriptor(target: object, key: string | number | symbol) {
  track(target, TrackOpTypes.GET, key)
  return Reflect.getOwnPropertyDescriptor(target, key)
}

This makes Object.prototype.hasOwnProperty.call(obj, 'a') works.

Edit:

Did some research, some basic semantics, such as [[Get]]/[[Set]]/[[Delete]] etc. all depend on O.[[GetOwnProperty]](P), this is where the devil is, making it impossible to intercept getOwnPropertyDescriptor to reach the goal.

[LinusBorg]

@HcySunYang Do I read your last comment correctly: Are we stuck here?

[HcySunYang]

Except for the solution given by this PR, I can't think of a better way.

Removing my change request as this need some guidance from Evan I think

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[yyx990803]

I noticed this fix is not granular: i.e. it would trigger even when unrelated keys are added or deleted.

More precise tracking can be achieved by returning an instrumented version of hasOwnProperty on reactive objects, as implemented in 588bd44.