将.change函数中变量的值传递并更新到全局变量Jquery

我正在寻找一种方法，将值数组从.change(function{})中的var selectedId = []传递到全局var globalId = []。所以每次selectedId中的值发生变化时，我都希望有一个像selectedId.update(globalId)或selectedId = globalId.update()这样的函数来更新全局id，但我不知道如何编写这部分。最终，我可以在其他更改功能中使用最新的globalId。这是我的代码

$(function(){
    var globalId = [];
    $("#listbox1").change(function(){
        var selectedId =[];
        //get each selection
        $.each(selectedId , function (fIndex, fValue) {
            $.each(this.options, function (value, option) {
                if (this.selected) {
                    selectedId.push(option.value);
                }
            });
        });
        // send value to globalId 
        selectedId = globalId; // how to keep globalId up-to-date 
        // for everytime selectedId changes
        $.ajax({
            //....
            traditional: true, 
            data:{"// id in the controller": selectedId},
            success{...},
            error{...}
        });//end ajax
    });//end listbox1 change
    $("#listbox2").change(function(){
        var selectedId2 = [];
        // same each function to get selected <option>s as listbox1
        $.each{...
            $each{...
            };
        };
        $.ajax({
            //...
            data:{
                "//id1 in the controller": selectedId2, 
                "//id2 in the controller": globalId 
            },// this is the reason why I want to pass those values from listbox1  
            //to globalId so that I can use these two arrays in my controller function
            success{...},  
            error{}              
        });
    })//end listbox2 change
});//end ready

如果有人有解决这个问题的想法，我将不胜感激。

谢谢！

Kevin