JS 简单的2级下拉框 大家可以自行扩展

以前都是用的服务器端的控件，绑定数据很随意，级联也很随意，现在要考虑用客户端控件，突然有点蛋疼，以前没怎么写过，今天认真写一个

在网上找得例子，再完善一下：嘻嘻

<script type="text/javascript">
    var cityArr=[];
    cityArr['Shanghai']=[
        {txt:'zhabei',val:'zhabei'},
        {txt:'huangpu',val:'huangpu'},
        {txt:'baoshan',val:'baoshan'},
        {txt:'xuhui',val:'xuhui'},
        {txt:'yangpu',val:'yangpu'},
        {txt:'hongkou',val:'hongkou'}
    ];
   
    cityArr['Jiangsu'] = [
             {txt:'nanjing', val:'nanjing'},         
             {txt:'wuxi', val:'wuxi'},        
             {txt:'xuzhou', val:'xuzhou'},        
             {txt:'suzhou', val:'suzhou'},        
             {txt:'nantong', val:'nantong'},        
             {txt:'huaiyin', val:'huaiyin'},        
             {txt:'yangzhou', val:'yangzhou'},        
             {txt:'zhenjiang', val:'zhenjiang'},        
             {txt:'changzhou', val:'changzhou'}    
    ];
   
    function setCity(province)
    {
        setSelectOption('city',cityArr[province],'-please select-');
    }
   
    function noneSelected(province)
    {
        removeOptionsExcept('city');
    }
    </script>

    <script type="text/javascript">
    function setSelectOption(selectObj,optionList,firstOption,selected)
    {
        if(typeof selectObj!='object')
        { selectObj=document.getElementById(selectObj) };
       
        //Empty the select
        removeOptions(selectObj);
       
        var start=0;
       
        if(firstOption)
        {
            selectObj.options[0]=new Option(firstOption,'');
            start ++;
        }
       
        var len=optionList.length;
       
        for(var i=0;i<len;i++)
        {
            selectObj.options[start]=new Option(optionList[i].txt,optionList[i].val);
           
            if(selected==optionList[i].val)
            {
                selectObj.options[start].selected=true;
            }
            start ++;
        }
    }
   
    function removeOptions(selectObj)
    {    
        if (typeof selectObj != 'object')    
        {         selectObj = document.getElementById(selectObj);     }
              // 原有选项计数    
        var len = selectObj.options.length;     
        for (var i=0; i < len; i++)    
        {        
            // 移除当前选项        
            selectObj.options[0] = null;    
        }
    }

    function removeOptionsExcept(selectObj)
    {
        if (typeof selectObj != 'object')    
        {         selectObj = document.getElementById(selectObj);     }
              // 原有选项计数    
        var len = selectObj.options.length;     
        for (var i=0; i < len; i++)    
        {        
            // 移除当前选项        
            selectObj.options[0] = null;    
        }
       
        selectObj.options[0]=new Option('-please select-','');

    }
    </script>

<form id="form1" runat="server">
    <div>
    <select id="province" onclick="if(this.value != ''){ setCity(this.options[this.selectedIndex].value);}else{noneSelected(city)}">
    <option value="">-please select-</option>
    <option value="Jiangsu">Jiangsu</option>
    <option value="Shanghai">Shanghai</option>
    </select>
   
    <select id="city">
    <option value="">-please select-</option>
    </select>
    </div>
    </form>

很简单 3级4级一样搞