jquery 控制freetextbox控件的长度

Question

控制 freetextbox 长度的jquery该如何写哇 
ASP 里边写了个
<FTB:FreeTextBox ID="FreeTextBox1" runat="server" Width="550px"></FTB:FreeTextBox>
要如何才能用jquery把他的utf-8格式长度限制在4000个以内并且还能显示还能动态剩下多少个字啊？

Answer 1

一: maybe can not support
<FTB:FreeTextBox ID="txtDescription" runat="Server" AutoGenerateToolbarsFromString="false"
                                        BackColor="White" EnableHtmlMode="false" clientSideTextChanged="FtbSetOnTime(this,500)" Width="770px" Height="150px" BreakMode="LineBreak" />
function FtbSetOnTime(ftbobj, maxlength) {
            var nLength = ftbobj.document.body.text.length;
            if (nLength > maxlength) {
                ftbobj.document.body.text.substring(0, maxlength);
            }
        }二: have test it ok
<FTB:FreeTextBox ID="txtDescription" runat="Server" EnableHtmlMode="false" AutoGenerateToolbarsFromString="false"
                                        BackColor="White" Width="770px"
                                        Height="150px" BreakMode="LineBreak" />
                                    <asp:RegularExpressionValidator ID="revTxtDescription" runat="server"  ControlToValidate="txtDescription" SetFocusOnError="true" ErrorMessage="RegularExpressionValidator"
                                        ValidationExpression="^(\s|\S){0,500}$" ForeColor="Red">The field's maxlength is must less than or equal to 500.</asp:RegularExpressionValidator>

Answer 2

jquery or:
 $("input[id$='btHeaderSave'],input[id$='NextToDetail']").live("click", function () {
                var $obj = $(document.getElementById('MainContent_txtDescription_designEditor').contentWindow.document.body);
                var flag = 0;
                var ss = $obj.text();
                $obj.blur(function () {
                    if ($(this).text().replace(/[ ]/g, "") != "")
                        $("#ftbDesc").hide();
                });
                if (ss.replace(/[ ]/g, "") == "") {
                    $("#ftbDesc").show();
                    $("#ftbDesc").text("*The filed is required.");
                    flag = 1;
                } else {
                    $("#ftbDesc").hide();
                }
                if ($("#MainContent_drpCallingEntity_txtEdit").val().toLowerCase() != $("#MainContent_drpCallingEntity_ddlSelect").find("option:selected").text().toLowerCase()) {
                    flag = 1;
                    $("#callspan").show();
                } else { $("#callspan").hide(); }
                if (flag == 1)
                    return false;
            })