JavaScript / jQuery：更改事件選擇不觸發

Question

我遇到這個問題，試圖讓一個單獨的函數在for ... in循環中在dropdown列表的“更改”事件上附加多個單獨的函數。 $('select')對象頂部沒有方法'on'是Chrome調試器檢測到的Type錯誤。

這是我的代碼：（我對JavaScript / jQuery的了解不多，所以請耐心等待我的編碼）

function AKaizerDropdown(HiddenFeild) {     //#id of hidden field passed as parameter
var select = $('select'); // select object assigned to variable
var selectcount = 0;
var Selecthold=new Array();

for (select in this) {

    select.on('change', function() {
        var SelectedIndex = this.attr('selectedIndex');
        selecthold[selectcount] = [select.attr('id'), selectedindex];         
        //Select ID and Selected index assigned as an array into Selecthold Array element
    });

    selectcount +=1; 

}
var item= new array();

//Elements in selecthold array printed onto hidden field 
for (item in selecthold) {
    $(HiddenFeild).val += item[0] + item[1]; //Assigns values to element Hiddenfield in DOM
}

}

編輯代碼：

 $.fn.AKaizerDropdown = function (HiddenFeild) {

var select_ = $(this).find('select'); 
var selectcount = 0;
var Selecthold=new Array();

select_.each(function () {

    $(this).on('change', function () { //everything runs fine except dropdownlist doesn't enter into this event when an item is chosen
        var SelectedIndex = this.selectedIndex;
        Selecthold[selectcount] = [this.id, Selectedindex];

    });

});

var button_ = $(this).find('input')
button_.on('click', function () {
    for (item in Selecthold) {
        $(HiddenFeild).val += item[0] + item[1]+','; //Assigns values to element Hiddenfeild in DOM seperated by ","
    }
});

}

某些固定代碼仍然無法正常工作

這是我將其連接到彈出式Bootstrap（twitter 2.3.2）的部分。

//think the problem lies here where the pop up seems to re-render the same same html found in ($#KaizerDragon") where all JavaScript is probably discarded?

$("#ContentPlaceHolder1_ADragonTreeviewt41").popover({
    html: true, container: 'body',
    trigger: 'click',
    content: function () {

        $(function () {
            $("#KaizerDragon").AKaizerDropdown();
        });
        return $("#KaizerDragon").html();

    }

}）;

所以我的問題是如何糾正上述代碼以獲得預期的輸出（如代碼中的注釋所示）？

Answer 1

你是在宣告

var select = $('select'); // select object assigned to variable

但是然后覆蓋您的for循環中的值

for (select in this) ...

也就是說，循環內部的select與您上面聲明的不同。

Answer 2

嘗試這樣的事情

            select.each(function(){
                 $(this).on('change', function() {
                    var SelectedIndex = this.selectedIndex;
                    Selecthold[selectcount] = [this.id, SelectedIndex];         
                    //Select ID and Selected index assigned as an array into Selecthold Array element
                });

            })