在laravel和js中为州及其城市选择输入

Question

我有一个省份表和一个城市表。现在，我为州和城市选择了两个输入，当用户选择该州的州显示给用户时。 我的代码在这里：

<select name="State" id="State" class="input" onChange="setcities();">
  <option value="a">a</option>
    @foreach($provinces as $province)
     <option value="{{$province->name}}">{{$province->name}}</option>
    @endforeach
</select>
<select name="City" id="city" class="input" onChange="setcities();">
  <option value="">select city!</option>
</select>

JavaScript代码是：

<script type="text/javascript">
    var cities = [];
    cities['a'] = ['maragheh','tabriz','tehran'];

    function setcities() {
        stateSel = document.getElementById('State');
        cityList = cities[stateSel.value];
        changeSelect('city', cityList, cityList);

    }


    function changeSelect(fieldID, newOptions, newValues) {
        selectField = document.getElementById(fieldID);
        selectField.options.length = 0;
        for (i = 0; i < newOptions.length; i++) {
            selectField.options[selectField.length] = new Option(newOptions[i], newValues[i]);
        }
    }

    function addLoadEvent(func) {
        var oldonload = window.onload;
        if (typeof window.onload != 'function') {
            window.onload = func;
        } else {
            window.onload = function () {
                if (oldonload) {
                    oldonload();
                }
                func();
            }
        }
    }

    addLoadEvent(function () {
        setcities();
    });
</script>

如何从数据库中获取城市并设置其状态？ 如何赋予城市价值选项并保存到数据库？