javascript 级联一

//更改创新类型小类
function changeInnSmall(big_id){
	if(big_id==''){
	    var obj=document.getElementById('ach_inn_small_classid');  
        obj.options.length=0;
		obj.options.add(new Option("请选择",""));
	}else{
	    var obj=document.getElementById('ach_inn_small_classid');  
        obj.options.length=0;
        var ajax = {
		  url: "<?php echo DT_PATH; ?>admin/ach_inn_small_list.inc.php", data: {bid:big_id}, type: 'POST', dataType: 'json', cache: false,
		  success: function(data, statusText) {
		      var name="";
		      var id="";
		      if(data==undefined){
		          obj.options.add(new Option("请选择",""));
			  }
			  
			  
			  for(var i=0;i<data.length;i++){
				 name=data[i].name;
				 id=data[i].id;
				 obj.options.add(new Option(name,id));
			   }
		
		  },
		  error: function(httpRequest, statusText, errorThrown) {
		          alert('数据请求时发生错误，请稍后"' + errorThrown + '"', '错误提示', 300, 100);
		  }
		  };
		  $.ajax(ajax);
		  return false;   	
	}
}