javascript - 0x800a138f - JavaScript 运行时错误 : Unable to get property 'value' of undefined or null reference

Question

我写了一个 javascript 代码来比较来自 2 个文本框的 2 个日期

     function CompareDates() {
            var fdate = document.getElementById('txtFromDate');
            var edate = document.getElementById('txtToDate');
            var FromDate = fdate.value.split('/');
            var EndDate = edate.value.split('/');
            var val = 'false';

            if (parseInt(FromDate[2]) < parseInt(EndDate[2])) {
                val = 'true';
                return true;
            }
            else if (parseInt(FromDate[2]) == parseInt(EndDate[2])) {
                if (parseInt(FromDate[0]) < parseInt(EndDate[0])) {
                    val = 'true';
                    return true;
                }
                else if (parseInt(FromDate[0]) == parseInt(EndDate[0])) {
                    if (parseInt(FromDate[1]) <= parseInt(EndDate[1])) {
                        val = 'true';
                        return true;
                    }
                }
            }
            if (val == "false") {
                alert("FromDate Always Less Than ToDate");
                return false;
            }
        }

html代码是

     <asp:TextBox ID="txtFromDate" runat="server" Width="150px" />
     <ajaxToolkit:CalendarExtender CssClass="MyCalendar" runat="server"
                                   ID="ceFromDate"
                                   TargetControlID="txtFromDate"
                                   Format="dd/MM/yyyy" />
    <asp:TextBox ID="txtToDate" runat="server" Width="150px" />
    <ajaxToolkit:CalendarExtender CssClass="MyCalendar" runat="server" 
                                  ID="ceToDAte"
                                  TargetControlID="txtToDate"
                                  Format="dd/MM/yyyy" />

     <asp:Button ID="btnGenerate" runat="server" CssClass="button"
                 Text="Generate" OnClientClick="if(!CompareDates()) return false;" 
                 OnClick="btnGenerate_Click" />

问题是页面在 chrome 中运行良好，但是当我在 IE 中运行我的应用程序时它抛出错误

0x800a138f - JavaScript runtime error: Unable to get property 'value' of undefined or null reference

请帮助我克服这个问题。

Answer 1

错误在这里:

    var fdate = document.getElementById('txtFromDate');
    var edate = document.getElementById('txtToDate');

问题是txtFromDate 和txtToDate 是控件的服务器名称，而不是客户端名称(从浏览器查看页面源)。

试试这个:

    var fdate = document.getElementById('<%=txtFromDate.ClientID%>');
    var edate = document.getElementById('<%=txtToDate.ClientID%>');