jQuery.fn.CascadingSelect = function(target, url, options, endfn) {
    $.ajaxSetup({ async: false });
    if (target[0].tagName != "SELECT") throw "target must be SELECT";
    if (url.length == 0) throw "request is required";
    if (options.parameter == undefined) throw "parameter is required";

    this.change(function() {
        var newurl = "";
        urlstr = url.split("?");
        //获取选择项的索引
        //        var index = $(this).get(0).selectedIndex;

        newurl = urlstr[0] + "?" + options.parameter + "=" + $(this).val() + "&" + urlstr[1];
        //        newurl = urlstr[0] + "?" + options.parameter + "=" + $(this).get(0).options[index].text + "&" + urlstr[1];
        
        target.FillOptions(newurl, options);
        if (typeof endfn == "function") endfn();
    });
}

jQuery.fn.AddOption = function(text,value,selected,index){
    option = new Option(text,value);            
	this[0].options.add(option,index);
	this[0].options[index].selected = selected;
}