How to set conditions for the output of certain blocks from JSON?

Question

JavaScript

Hello! There is json and there is a script, there are different blocks (product reviews with and without comments). How to write in a script that, depending on the content, exactly the block that is specified there would be loaded in JSON?
My JSON:

{
  "review": [
    {
            "id": "1",
      "foto": "/images/content/avatar-review.jpg",
      "name": "Rosa",
      "text": "ТЕКСТ.",
      "star": "3",
      "date": "22.10.2015 17:21"
    }
   ]
}

JSON does not yet contain data for the block with comments. Tell me how to be? What do I need to do next? What is the condition?