Select

Schema:

{
  "type": "object",
  "properties": {
    "type": {"type": "string", "pattern": "^form-field$"},
    "id": {"type": "string", "pattern": "^[0-9a-f]{8}-([0-9a-f]{4}-){3}[0-9a-f]{12}$"},
    "machine_name": {"type": "string"},
    "data": {
      "type": "object",
      "properties": {
        "uid": {"type": "string","pattern": "^form-select$"},
        "title": {"type": "string"},
        "value": {"type": "string"}
      }
    }
  },
  "required": ["id", "type", "data"]
}

Examples:

Given "Select" form element on a component set up like so

And used on Node layout canvas like so

JSON:API output for this form field will be this:

{
  "type": "form-field",
  "id": "6ec8c805-296c-44d0-a8ba-91cbd36dfc67",
  "machine_name": "select",
  "data": {
    "uid": "form-select",
    "title": "Select",
    "value": "two"
  }
}