使用JavaScript和JQuery，我如何维护一个动态更新的HTML选择元素的选择状态

仍然不能100%确定你在问什么，但似乎这应该做你正在寻找的，是几行代码。

(function () {
        function updateDuplicates() {
            $("#duplicates").find("select").html($("#original").html());
            $('#duplicates select').each(function () {
                var lastSelectedValue = $(this).data('lastSelectedValue');
                $(this).val(lastSelectedValue || $(this).val());
            });
        }
        $(document).ready(function () {
            $('button:contains(remove)').bind('click', function (e) {
                e.preventDefault();
                var original_select = document.getElementById('original'),
                current_selected = original_select.selectedIndex;
                original_select.remove(original_select[current_selected]);
                if (original_select.options.length) {
                    original_select.options[current_selected < original_select.options.length ? current_selected : current_selected - 1].selected = 'selected';
                }
                updateDuplicates();
            });
            $('button:contains(add/copy)').bind('click', function (e) {
                e.preventDefault();
                var original_select = document.getElementById('original'),
                new_option = document.createElement('option');
                new_option.text = 'Option #' + original_select.length;
                new_option.value = new_option.text;
                document.getElementById('original').add(new_option);
                original_select.options[original_select.options.length - 1].selected = 'selected';
                updateDuplicates();
            });
            $('#duplicates select').bind('change', function () {
                $(this).data('lastSelectedValue', $(this).val());
            });
        } ());
    } ());

<button>add/copy</button>
<button>remove</button>

将当前选中的项/值设置为某个变量，然后进行操作，最后重新选择值

好吧，我想我有一个可行的解决方案，如果不是一个笨拙的方法。棘手的部分不是向原始列表添加值，因为添加的选项总是在列表的末尾。问题出现在删除select选项时，因为这样做会更改当前选定的索引。我在Mac上使用谷歌浏览器进行了测试，没有出现任何错误。我对代码进行了注释，以演示如何处理我的解决方案:

<form>
<div id="duplicates">
  <!--// Each of these select lists should maintain their currently selected index //-->
  <select>
  </select>
  <select>
  </select>
  <select>
  </select>
</div>
<div>
  <!--// Using a generic function to capture each event //-->
  <input type="button" value="add/copy" onClick="updateDuplicates('add');" />
  <input type="button" value="remove" onClick="updateDuplicates('remove');" />
  <select id="original">
  </select>
</div>
<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js"></script>
<script type="text/javascript">
    function updateDuplicates(editMode){
        ///* Capture the selectedIndex of each select list and store that value in an Array *///
        var original_select = document.getElementById('original');
        var current_selected = new Array();
        $("#duplicates").find("select").each(function(index, element) {
            current_selected[index] = element.selectedIndex;
        });
        switch(editMode){
            case "add":
                var new_option = document.createElement('option');
                new_option.text = 'Option #' + original_select.length;
                new_option.value = new_option.text;
                original_select.add(new_option);
                original_select.options[original_select.options.length-1].selected = 'selected';
                ///* Traverse each select element and copy the original into it, then set the defaultSelected attribute for each *///
                $("#duplicates").find("select").each(function(index, element){
                    $(element).html($("#original").html());
                    ///* Retrieve the currently selected state stored in the array from before, making sure it is a non -1 value, then set the defaultSelected attribute of the currently indexed element... *///
                    if(current_selected[index] > -1){
                        element.options[current_selected[index]].defaultSelected = true;
                    }
                });
                break;
            case "remove":
                var current_index = original_select.selectedIndex;
                original_select.remove(original_select[current_index]);
                ///* Thou shalt not remove from thine empty list *///
                if(original_select.options.length){
                    original_select.options[current_index > 0?current_index - 1:0].selected = 'selected';
                }
                ///* Traverse each select element and copy the original into it... *///
                $("#duplicates").find("select").each(function(index, element){
                    $(element).html($("#original").html());
                    ///* Avoid operating on empty lists... *///
                    if(original_select.options.length){
                        ///* Retrieve the currently selected state stored in the array from before, making sure it is a non -1 value... *///
                        if(current_selected[index] > -1){
                            ///* If the stored index state is less or equal to the currently selected index of the original... *///
                            if(current_selected[index] <= current_index){
                                element.options[current_selected[index]].defaultSelected = true;
                            ///* ...otherwise, the stored index state must be greater than the currently selected index of the original, and therefore we want to select the index after the stored state *///
                            }else{
                                element.options[current_selected[index] -  1].defaultSelected = true;
                            }
                        }
                    }
                });
            }           
     }
</script>
</form>

有足够的空间来修改我的代码，以便可以将选项插入到当前选定的索引之后，而不是附加到原始选择列表的末尾。从理论上讲，一个多选择列表/菜单也应该工作。吃吧。

我相信这里的一个天才能够用比我的代码更干净、更漂亮的代码做同样的事情。感谢所有对我最初的问题进行评论和评论的人!欢呼。

如果您可以重置一点，我认为问题是您将选择列表的HTML设置为另一个列表的HTML。如果所有的底层html都被更改了，浏览器可能不会尝试保留当前选中的项。

所以，我认为你可能会尝试做的是显式地将选项元素添加到目标列表中。

试试这个。如果您选择了默认第一项以外的项并单击"添加"，请注意所选的项将被维护。因此，在管理目标列表项时，您需要更精确一些。

也许会有帮助，也许我没抓住重点。