以下是一些更正，这些参考来自

Here are some corrections taking reference from this page for script. In Controller:

 $s = Category::all()->where('parent_id','=','0');

查看:

<div class="form-group">
    {!! Form::label('category','Category:') !!}
    <select name="category" id="category" class="form-control input-sm">
        @foreach($s as $k)
            <option value="{{ $k['id'] }}">{{ $k['name'] }}</option>
        @endforeach
        {{--<option value="Dance And Music">Dance And Music</option>--}}
    </select>
</div>

<div class="form-group">
    {!! Form::label('subcategory','Subcategory:') !!}
    <select name="subcategory" id="subcategory" class="form-control input-sm">
        <option value=""></option>
    </select>
</div>

脚本:

        $(document).ready(function () { 
            $('#category').on('change',function(e){
            console.log(e);
            var cat_id = e.target.value;
            //console.log(cat_id);
            //ajax
            $.get('/ajax-subcat?cat_id='+ cat_id,function(data){
                //success data
               //console.log(data);
                var subcat =  $('#subcategory').empty();
                $.each(data,function(create,subcatObj){
                    var option = $('<option/>', {id:create, value:subcatObj});
                    subcat.append('<option value ="'+subcatObj+'">'+subcatObj+'</option>');
                });
            });
        });
    });

Routes.php

Routes.php

Route::get('/ajax-subcat',function () {
$cat_id = Input::get('cat_id');
$subcategories = DB::table('main_category')->where('parent_id','=',$cat_id)->lists('name');
return Response::json($subcategories);});