graaljs: Arrays passed to JS using ProxyArray do not mimic JS arrays

I have a Java host application that is executing JS scripts as guest using the Polyglot API. I would like to pass Java arrays (ArrayList) to the JS side and treat the array on the JS side as if it was a “native” JS array. As suggested in this SOF post: https://stackoverflow.com/questions/51707039/injected-members-from-the-host-language-to-arrive-to-guest-language-as-guest-lan I am using ProxyArray to achieve that. Specifically, I am using ProxyArray.fromArray() to pass the Java ArrayList to the JS side using bindings:

Value guestLanguageBindings = context.getBindings("js"); guestLanguageBindings.putMember("arrParamName", ProxyArray.fromArray(arrayArg));

However in the JS side (guest language) the array is not seen as a JS array, instead it is of type: org.graalvm.polyglot.proxy.ProxyArray (also a Java type). This prevents me from being able to use the array as if it were a regular JS array. Statements like arr[0] work, however specific calls such as arr.sort() fail.

The screenshot below illustrate a debugging session where variable is passed as described above with the resulting error.