I am trying to update a value inside of JSON running on a json-server via my React appliction. Each time I make the POST request it replaces all data inside of the JSON instead of updating it. I am not sure what I am missing.

The React App.js:

  //Update JSON
  const updateOptions = async () => { 
    const res = await fetch('http://localhost:5000/options', {
      method: 'POST',
      headers: {
        'Content-type': 'application/json'
      },
      body: JSON.stringify({score: 10})
    })
  }

When this function is called, it adds score: 10 to the JSON but removes everything else.

JSON Before:

{ "options": 
  {
    "gametype": "rand",
    "gamecat": 11,
    "score": 0
  }
}

JSON After:

{
  "options": {
    "score": 10
  }
}

I'm not sure why it's removing all other data from the JSON, what am I missing?