创建2级相互依赖的选择列表

Question

我浏览了StackOverflow并发现了几个问题/答案,但是我的情况并不准确.我跟着这个例子:

http://www.javascriptkit.com/javatutors/selectcontent2.shtml

我的JavaScript代码是这样的:

var cityList = document.selectionForm.cityListBox;
var cities = new Array();

cities[0] = "";
cities[1] = ["Eugene|eugeneValue", "Portland|portlandValue", "Salem|salemValue"];
cities[2] = ["Bellingham|bellinghamValue", "Onalaska|onalaskaValue", "Seattle|    seattleValue"];

function updateCities(cityGroup) 
{
    cityList.options.length = 0;

    if (cityGroup > 0)
    {
        for (i = 0; i < cities[cityGroup].length; i++)
        {
            cityList.options[cityList.options.length] = new Option(cities[cityGroup][i].split("|")[0], cities[cityGroup][i].split("|")[1]);
        }   
    }
}

我的HTML代码如下:

<form name="selectionForm">
    <select name="stateListBox" size="3" style="width: 150px" onchange="updateCities(this.selectedIndex);">
        <option selected>Select a State >></option>
        <option value="oregon">Oregon</option>
        <option value="washington">Washington</option>
    </select>

    <select name="cityListBox" size="3" style="width: 150px" onclick="alert(this.options[this.options.selectedIndex].value);">
    </select>
</form>

据我所知,这应该如上面的链接所描述的那样工作.我在JavaScript Kit网站上有过很棒的经历,但这次我觉得我错过了一些东西.

当我实际将其发布到页面时,我可以单击状态,但是没有任何内容出现在城市框中,如预期的那样.

谁能在这里看到问题？

任何帮助表示赞赏.

PS - 如果有一个我错过的双重帖子,我道歉.任何参考也非常感谢.

Answer 1

使用jQuery的更易读的解决方案,不要求你保持两个列表同步(状态和城市在javascript数据结构中定义)

HTML:

<form name="selectionForm">
    <select name="states" id="states" size="3" style="width: 150px">
        <option selected>Select a State >></option>
    </select>

    <select name="cities" id="cities" size="3" style="width: 150px"></select>
</form>

JavaScript的:

jQuery(function($) {
    initCities();

    function initCities() {
        var statesAndCities = {
            'Oregon': ['Eugene', 'Portland', 'Salem'],
            'Washington': ['Bellingham', 'Onalaska', 'Seattle']
        };

        //populate states
        $.each(statesAndCities,function(k,v){$('#states').append('<option>' + k + '</option>');});

        //populate cities
        $('#states').change(function(){
            var $cities = $('#cities');
            $cities.html("");
            var cities = statesAndCities[$(this).val()];
            $.each(cities,function(k,v){$cities.append('<option>' + v + '</option>');});
        });
    }

});

演示:

http://jsfiddle.net/82frv/1/