使用onchange。试试这个

<div class="form-group" >
                <label class="text-primary" dir="rtl" for="exampleFormControlSelect1">{{trans('admin.theplace')}}</label>
                <select class="form-control" name="place" data-style="btn btn-link" id="exampleFormControlSelect1">
                    @foreach($places as $pt)
                    <option value="{{$pt->id}}" {{ ($pt->name)? "selected" : '' }}  >{{$pt->name}} onchange="dropdown('{{$p->id}}')"</option>
                    @endforeach
                </select>
            </div>
            <div class="form-group" >
                <label class="text-primary" dir="rtl" for="exampleFormControlSelect1">{{trans('admin.itemCats')}}</label>
                <select class="form-control" name="itemcat" id="category" data-style="btn btn-link" id="exampleFormControlSelect1">
                    @foreach($categories as $cat)
                    <option value="{{ $cat->id }}" {{ (isset($cat->name))? "selected" : '' }}  >{{$cat->name}}</option>
                    @endforeach
                </select>
            </div>

在api.php上编写时,在url上添加如下api

'/get-list'

那你就叫它

 /api/get-list