dynamic select drop down Laravel 5.3

saya ingin membua dynamic select drop down di laravel 5.3 tetapi gagal,tidak muncul error tetapi ketika category dipilih subcategory nya gak muncul. mohon bantuannya.

ini adalah code dari view saya

{{ Form::open(['url' => 'foo/bar', 'files' => true]) }}
        <input type="hidden" name="_token" value="{{ csrf_token() }}">

        <div class="form-group">
          <label class="sr-only">Categories</label>
          <select class="form-control input-sm" name="category" id="category">
            @foreach( $categories as $data )

            <option value="{{ $data->id }}"> {{ $data->name }}</option>

            @endforeach
          </select>
        </div>

        <div class="form-group">
          <label class="sr-only">Subcategories</label>
          <select class="form-control input-sm" name="subcategory" id="subcategory">
            <option value=""></option>
          </select>
        </div>
{{ Form::close() }}

ini adalah JS saya

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.12.4/jquery.min.js"></script>

<script language="JavaScript" type="text/JavaScript">

    $('#category').on('change', function(e){
      console.log(e);
      var cat_id = e.target.value;

      //ajax

      $.get('/ajax-subcat/' + cat_id, function(data){

        $('#subcategory').empty();

        $.each(data, function(index, subcatObj){
          $('#subcategory').append('<option value="'+subcatObj.id+'">'+subcatObj.name+'</option>');
        });
      });
    });

</script>

ini adalah route saya

Route::get('/', function () {
	$all = new Category;
	$categories = $all->get();
    return view('index', compact('categories'));
});

Route::put('/ajax-subcat/{id}', 'HomeController@ajax');

ini adalah Controller saya dan saya

    public function ajax(Request $request, $id)
    {

        $all = new Subcategory;

        $subcategories = $all->where('category_id', $id)->first();

        return response()->json($subcategories);
    }

ini adalah migration Category

    public function up()
    {
        Schema::create('categories', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->timestamps();
        });
    }

dan ini adalah migration Subcategory

    public function up()
    {
        Schema::create('subcategories', function (Blueprint $table) {
            $table->increments('id');
            $table->string('name');
            $table->integer('category_id')->unsigned();
            $table->timestamps();

            $table->foreign('category_id')->references('id')->on('categories');
        });
    }