jquery实现级联下拉列表

<script type="text/javascript">
  /**
* 级联下拉列表
*/
$(function(){
  var base = getRootPath();
  var url = base + "/util/classtype!rootClassTypeList.action";
 
   $.post(url, function(data) {  

  var selectObj = $('#s1').get(0);
  initOptions(selectObj, data); 

},'JSON');

$('#s1').change(function() {
$('#s2').empty();
    var base = getRootPath();
    var url = base + "/util/classtype!subClassList.action";
$.post(url, {'id' : $('#s1').val()}, function(data) {
var selectObj = $('#s2').get(0);
initOptions(selectObj, data);
});

},'JSON');
 
  });
</script>


/**
* 初始化options
* @param selectObject select对象
* @param list 数组 格式为{"value" : key, "label" : label}
*/
var initOptions = function(selectObject, list) {
    if (selectObject !== null && selectObject !== undefined) {
        var options = selectObject.options;      
        options.length = 0;
        // 添加一个空选项
        var nullOption = new Option("", "", false, false);
        options.add(nullOption);
        if (list !== null && list !== undefined && list !== "[]") {
       
         var json = eval(list);
    
            for (var i in json) {
                var item = json[i];
               
                if (item !== null && item !== undefined) {
                    var value = item.key;
                    var label = item.label;
                    // label 与 value 必须同时存在才是一个完整的数据
                    if (value !== null && value !== undefined && label !== null && label !== undefined) {
                        var option = new Option(label, value, false, false);
                        options.add(option);
                    }
                }
            }
        }
    }
};