I've used the example code to try and query the Subdivisions_States_Provinces endpoint for results within a specific country code and used a couple of country codes to test, but nothing is returned.

Any assistance would be greatly appreciated.

Regards, Paul

The same happens when querying the cities endpoint.

I am using the javascript examples

You have to use the country object id (and not the code). For example, if you search for US, you will see this response:

{
  "results": [
    {
      "objectId": "BXkZTl2omc",
      "code": "US",
      "name": "United States",
      "native": "United States",
      "phone": "1",
      "continent": {
        "__type": "Pointer",
        "className": "Continent",
        "objectId": "vZNZcahFvu"
      },
      "capital": "Washington D.C.",
      "currency": "USD,USN,USS",
      "emoji": "🇺🇸",
      "emojiU": "U+1F1FA U+1F1F8",
      "createdAt": "2019-12-11T08:14:17.654Z",
      "updatedAt": "2020-04-13T18:19:25.532Z",
      "geonameid": 6252001,
      "shape": {
        "__type": "Pointer",
        "className": "Shape",
        "objectId": "sb3piMeMV9"
      },
      "languages": {
        "__type": "Relation",
        "className": "Language"
      },
      "cities": {
        "__type": "Relation",
        "className": "City"
      },
      "timezones": {
        "__type": "Relation",
        "className": "Timezone_Time_Zones_Dataset"
      },
      "provinces": {
        "__type": "Relation",
        "className": "Subdivisions_States_Provinces"
      }
    }
  ]
}

So, searching for US cities, would require you to use the following request:

(async () => {
        const where = encodeURIComponent(JSON.stringify({
          "country": {
            "__type": "Pointer",
            "className": "Country",
            "objectId": "BXkZTl2omc"
          }
        }));
        const response = await fetch(
          `https://parseapi.back4app.com/classes/City?limit=10&where=${where}`,
          {
            headers: {
              'X-Parse-Application-Id': 'mxsebv4KoWIGkRntXwyzg6c6DhKWQuit8Ry9sHja', // This is the fake app's application id
              'X-Parse-Master-Key': 'TpO0j3lG2PmEVMXlKYQACoOXKQrL3lwM0HwR9dbH', // This is the fake app's readonly master key
            }
          }
        );
        const data = await response.json(); // Here you have the data that you need
        console.log(JSON.stringify(data, null, 2));
      })();

Thanks for the advice @davimacedo. I also realised that there's an issue with the endpoint names in the generated code. The one for countries is correct, but the one for subdivisions is not 'Subdivisions_States_Provinces', it's 'Continentscountriescities_Subdivisions_States_Provinces' and the one for cities is not 'City', it's 'Continentscountriescities_City'. Having got that right, and with your advice, I got it all working.

I am glad you figured it out. When talking about the endpoint names, please note that they change wether you are using the fake app or your own app. I mean, if you select one of your apps in the step 1 of the get started, it should generate the code with the right names.