Using the Connect Javascript API in Confluence Cloud, the AP.context.getContext() function can be used to retrieve the following information on a page:

{
  "confluence": {
    "content": {
      "type": "page",
      "version": "1",
      "id": "7363198983"
    },
    "space": {
      "key": "SP",
      "id": "7356710917"
    }
  }
}
 

It would be beneficial if the context object, or the AP._data.options object, also contained the ownerId of a page to avoid having to make a separate API call to fetch that information