asp.net - 当我向选择添加选项时，选择会变窄

Question

继承了一个应用程序，该应用程序的页面有一个调用 javascript 函数 addValueClick() 的链接，当我执行此操作时，会弹出一个对话框，我输入一些文本，然后将文本放入选择框中。每次将新选项添加​​到选择中时，它都会变窄约 5 个像素。我不明白为什么会发生这种情况，但它只发生在 IE7 中

这是 JavaScript:

function addValueClick()
{
    var newValue = prompt("Please enter a new value.","");
    if (newValue != null && newValue != "")
    {
        var lst = document.getElementById("lstValues");
        var opt = document.createElement("option");
        opt.setAttribute("selected", "true");
        opt.appendChild(document.createTextNode(newValue));
        lst.appendChild(opt);
        updateBtns();
        copyValues();
    }
}

function copyValues()
{
    var frm = document.forms[0];
    var lst = frm.elements["lstValues"];
    var hid = frm.elements["hidValues"];
    var xml = "<root>";
    for (var i = 0; i < lst.options.length; i++)
    {
        xml += "<value seq_num=\"" + (i + 1) + "\">" +
          lst.options[i].text + "</value>";
    }
    xml += "</root>";
    hid.value = xml;
}

function updateBtns()
{
    var lst = document.getElementById("lstValues");
    var iSelected = lst.selectedIndex;
    var lnkEdit = document.getElementById("lnkEditValue");
    var lnkDelete = document.getElementById("lnkDeleteValue");
    var lnkUp = document.getElementById("lnkValueUp");
    var lnkDown = document.getElementById("lnkValueDown");
    if (iSelected == -1)
    {
        lnkEdit.style.visibility = "hidden";
        lnkDelete.style.visibility = "hidden";
        lnkUp.style.visibility = "hidden";
        lnkDown.style.visibility = "hidden";
    }
    else
    {
        lnkEdit.style.visibility = "visible";
        lnkDelete.style.visibility = "visible";

        if (iSelected == 0)
            lnkUp.style.visibility = "hidden";
        else
            lnkUp.style.visibility = "visible";

        if (iSelected == lst.options.length - 1)
            lnkDown.style.visibility = "hidden";
        else
            lnkDown.style.visibility = "visible";
    }
}

编辑: HTML，实际上是ASP.NET。 listValueChanged() 方法所做的只是调用上面的 updateButtons()。

<tr>
    <TD class=body vAlign=top noWrap align=right><b>Values:</TD>
    <TD class=body vAlign=top noWrap align=left><asp:ListBox id="lstValues" runat="server" onchange="lstValuesChange();" Rows="9" onselectedindexchanged="lstValues_SelectedIndexChanged"></asp:ListBox></TD>
    <TD class=body vAlign=top noWrap align=left>
        <TABLE id="Table2" cellSpacing="2" cellPadding="2" border="0">
            <TR>
                <TD noWrap>
                    <asp:HyperLink id="lnkAddValue" runat="server" NavigateUrl="javascript:addValueClick();">Add</asp:HyperLink></TD>
            </TR>
            <TR>
                <TD noWrap>
                    <asp:HyperLink id="lnkEditValue" runat="server" NavigateUrl="javascript:editValueClick();">Edit</asp:HyperLink></TD>
            </TR>
            <TR>
                <TD noWrap>
                    <asp:HyperLink id="lnkDeleteValue" runat="server" NavigateUrl="javascript:deleteValueClick();">Delete</asp:HyperLink></TD>
            </TR>
            <TR>
                <TD noWrap>&nbsp;</TD>
            </TR>
            <TR>
                <TD noWrap>
                    <asp:HyperLink id="lnkValueUp" runat="server" NavigateUrl="javascript:valueUpClick();">Up</asp:HyperLink></TD>
            </TR>
            <TR>
                <TD noWrap>
                    <asp:HyperLink id="lnkValueDown" runat="server" NavigateUrl="javascript:valueDownClick();">Down</asp:HyperLink></TD>
            </TR>
        </TABLE>
    </TD>
</TR>

Answer 1

它可能与 html 的关系比与脚本的关系更大。 select 包含什么？根据JS，我认为这里没有任何问题。