比较两个数组并过滤掉哪些数据和哪些数据可用

I am struggling with the following

I have a table called plates

 {
        "id": 1,
        "plate_container_id": 1,
        "plate_container_slot": 1,
        "deleted_at": null,
        "created_at": "2015-10-21 18:42:26",
        "updated_at": "2015-10-21 18:57:27"
}

And I have table called platecontainers

{
        "id": 1,
        "name": "Prof. Carroll Smitham PhD",
        "number_of_slots": 7,
        "description": "Asperiores reiciendis",
        "created_at": "2015-10-21 18:42:25",
        "updated_at": "2015-10-21 18:42:25"
    }

What I want is -- When he user selects a platecontainer the number_of_slots are compared with the one in plates table (which is plate_container_slot) and checks which slots are already occupied (or taken) by any other plates. If the slot is taken, the user gets to see those as grayed out, otherwise they are available to use.

Now I am using Angularjs and Laravel 5. Would someone please tell me what is the best way to achieve this? And how to do it? I am little confused about it.