ways to prevent scripts from accessing certain built-in features

[YJ]

Hi v8-users,

In certain situations we want user scripts to run in a context where the scripts don't get to use some of the newer ECMAScript features, for instance, Atomics, typed arrays etc. What is the recommended way to achieve that?

Any pointers are appreciated.

[Ben Noordhuis]

Delete the corresponding globals from the global object
(`v8::Context::Global()`) before you start executing JS code. Won't
work for everything but will work for most things.

[YJ]

Thanks Ben. Will give that a shot.

I had experimented with interceptors but unfortunately I can't seem to return a normal global object from inside an global interceptor as accessing a property triggers that interceptor again.

[YJ]

A semi-related question, are the built-ins in global not enumerable for some reason ?

Basically the following code does not iterate over things like typed array constructors. Am I doing something wrong here ?

auto g = context->Global();  

Local<Array> props = g->GetPropertyNames();
const uint32_t length = props->Length(); // length is always 0 in a clean context

[YJ]

Well nm...something along the following line works for me.

  // Local<Array> props = g->GetPropertyNames(context,
  //                                          KeyCollectionMode::kOwnOnly,
  //                                          PropertyFilter::ALL_PROPERTIES,
  //                                          IndexFilter::kSkipIndices)
  //   .ToLocalChecked();

The default mode for PropertyFilter must have been the problem.

[Ben Noordhuis]

On Thu, Apr 12, 2018 at 10:29 AM, YJ <yang....@celigo.com> wrote:
> A semi-related question, are the built-ins in global not enumerable for some
> reason ?

That's per spec. Other JS engines work the same way.