Effectively yes, but not like that. You can access all native APIs with a marshalling layer which maps Javascript to Objective C or JAVA.

For example, when the Javascript parser sees

   var className = NSStringFromClass(NSArray);

The ObjectiveC side executes

    NSString *className = NSStringFromClass([NSArray class]);

Then creates a link between the JS object and the ObjectiveC object. Any methods/properties you access on the JS object, get executed or read from the native component.

It's really quite clever and why we use Nativescript to bring corporate apps to market quickly and cross platform while not worrying about the limitations of the Javascript bit, because you can always access the native APIs anyway.