How to convert v8 Value to Array

Question

I'm writing a c++ extension to v8, and want to pass an Array object into it. I see the incoming argument can be tested by IsArray(), but there isn't a ToArray().

How do you get access to its Length, and request elements by numeric index?

Handle<Value> MyExtension(const Arguments& args)
{
    Handle<Value> v = args[0];
    if(v->IsArray())
    {
        // convert to array, find its length, and access its members by index... ?
    }
...
}

Must be missing something obvious here. Object can return all its properties, but that's not quite what I was hoping for. Is there a way to get it as an Arrray?

Thanks for reading.

Answer 1

I wasn't able to find a way to convert or cast to Array. Maybe there's a way. But I found by doing object->IsArray(), object->get("length")->Uint32Value(), and object->get(int), I could just walk the array.

v8::Handle<v8::Object> obj;
// ... init obj from arguments or wherever ...

int length = 0;
if(obj->IsArray())
{
    length = obj->Get(v8::String::New("length"))->ToObject()->Uint32Value();
}

for(int i = 0; i < length; i++)
{
    v8::Local<v8::Value> element = obj->Get(i);
    // do something with element
}

Answer 2

The below is my succeeded code

v8::Handle<v8::Value> obj(args[0]);

 if(obj->IsArray()){

     v8::Local<v8::Array> arr= v8::Local<v8::Array>::Cast(args[0]);
     v8::String::Utf8Value key(arr->Get(0));
     v8::String::Utf8Value value(arr->Get(1));

 }

Answer 3

You should use Cast method of a handle to cast it to a different type:

v8::Handle<v8::Array> array = v8::Handle<v8::Array>::Cast(v);

Answer 4

i was able to get things working like this, its just a variation of the answer Vyacheslav Egorov gave

Local<Array> arr= Local<Array>::Cast(args[0]);
printf("size %d\n",arr->Length());
Local<Value> item = arr->Get(0);