Unity JS -> C# new array allocation marshalling

code.cs

using System;
using System.Runtime.InteropServices;
using UnityEngine;

public class code : MonoBehaviour
{
    void Start()
    {
        Method1();
        Method2();
    }

    // Method 1: malloc() memory on JS side, use IntPtr and Marshal.ReadIntPtr()
    //           and call back to JS side to free() to avoid memory leak
    // https://learn.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.marshal.readintptr?view=net-7.0

    [DllImport("__Internal")]
    public static extern IntPtr GetBytes(out int arrayLength);

    [DllImport("__Internal")]
    public static extern void nativeFree(IntPtr nativeArray);

    void Method1()
    {
        int arrayLength;
        IntPtr array = GetBytes(out arrayLength);
        Debug.Log($"Received array of length {arrayLength}");
        for(int i = 0; i < arrayLength; ++i)
            Debug.Log($"{i}: {Marshal.ReadIntPtr(array, i<<2)}");
        nativeFree(array); // Careful to avoid memory leak!
    }

    // Method 2: malloc() memory on JS side, use IntPtr and Marshal.Copy()
    //           and call back to JS side to free() to avoid memory leak
    // https://learn.microsoft.com/en-us/dotnet/api/system.runtime.interopservices.marshal.copy?view=net-7.0

    void Method2()
    {
        int arrayLength;
        IntPtr array = GetBytes(out arrayLength);
        Debug.Log($"Received array of length {arrayLength}");

        int[] csArray = new int[arrayLength];
        Marshal.Copy(array, csArray, 0, arrayLength);
        nativeFree(array); // Careful to avoid memory leak!

        foreach(int i in csArray)
            Debug.Log(i.ToString());
    }
}

code.jslib

mergeInto(LibraryManager.library, {
  GetBytes: function(arrayLength) {
    var len = (1 + Math.random() * 16) | 0;
    var array = _malloc(len<<2);
    for(var i = 0; i < len; ++i) HEAPU32[(array>>2)+i] = i;
    HEAPU32[arrayLength>>2] = len;
    return array;
  },

  nativeFree: function(nativeArray) {
    _free(nativeArray);
  }
});