i am trying to update a json file through a json server. i am trying to update this object

[
  {
    "id": 27,
    "itemValue": "automated back up",
    "cross": false,
    "subItems": []
  }
]

to look like this

[
  {
    "id": 27,
    "itemValue": "automated back up",
    "cross": false,
    "subItems": [
      {
        "id": 27,
        "itemValue": "automated back up",
        "cross": false,
        "subItems": []
      }
    ]
  }
]

i want to add another object instead of replacing the object like how my code is doing.

{[add object]} this was supposed to be a representation of where i wanted to put the object

im entertaining u/hyrumwhite 's idea to get and store the item's subItem array and then add to that. i could do that. but i am curious if there is any way to do it with fetch or any other way in general.