js判断文本框输入的内容是否一样

<%@ Page Language="C#" AutoEventWireup="true" CodeFile="ExaminationDetail.aspx.cs" Inherits="admin_ExaminationDetail" %><!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"><html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
    <title>无标题页</title>
    <link href="../Mystyle.css" rel="stylesheet" type="text/css" />
</head>
<body style="text-align: center">
    <form id="form1" runat="server">
 <br />
        <br />
        <br />
    <fieldset style="WIDTH: 454px; HEIGHT: 335px">
    <legend class="mailTitle">试题详细信息</legend>&nbsp; &nbsp; &nbsp;&nbsp;<br />
        <table align="center" border="0" cellpadding="0" cellspacing="0" style="height: 321px"
            width="344">
            <tr>
                <td style="height: 24px; text-align: right" width="87">
                    &nbsp;所属科目：</td>
                <td colspan="2" style="height: 24px; text-align: left">
        <asp:Label ID="lblkm" runat="server"></asp:Label>&nbsp;</td>
            </tr>
            <tr>
                <td style="text-align: right">
                    &nbsp;试题题目：</td>
                <td colspan="2" style="text-align: left">
        <asp:TextBox ID="txtsubject" runat="server" TextMode="MultiLine"></asp:TextBox>&nbsp;</td>
            </tr>
            <tr>
                <td style="text-align: right">
                    &nbsp;选项A：</td>
                <td colspan="2" style="text-align: left">
        <asp:TextBox ID="txtAnsA" runat="server" TextMode="MultiLine"></asp:TextBox>&nbsp;</td>
            </tr>
            <tr>
                <td style="text-align: right">
                    &nbsp;选项B：</td>
                <td colspan="2" style="text-align: left">
        <asp:TextBox ID="txtAnsB" runat="server" TextMode="MultiLine"></asp:TextBox>&nbsp;</td>
            </tr>
            <tr>
                <td style="text-align: right">
                    &nbsp;选项C：</td>
                <td colspan="2" style="text-align: left">
        <asp:TextBox ID="txtAnsC" runat="server" TextMode="MultiLine"></asp:TextBox></td>
            </tr>
            <tr>
                <td style="text-align: right">
                    &nbsp;选项D：</td>
                <td colspan="2" style="text-align: left">
        <asp:TextBox ID="txtAnsD" runat="server" TextMode="MultiLine"></asp:TextBox>&nbsp;</td>
            </tr>
            <tr>
                <td style="height: 27px; text-align: right">
                    &nbsp;正确选项：</td>
                <td colspan="2" style="height: 27px; text-align: left">
        <asp:RadioButtonList ID="rblRightAns" runat="server" RepeatDirection="Horizontal"
            RepeatLayout="Flow">
            <asp:ListItem Value="1">选项A</asp:ListItem>
            <asp:ListItem Value="2">选项B</asp:ListItem>
            <asp:ListItem Value="3">选项C</asp:ListItem>
            <asp:ListItem Value="4">选项D</asp:ListItem>
        </asp:RadioButtonList>&nbsp;</td>
            </tr>
            <tr>
                <td style="height: 29px; text-align: right">
                    &nbsp;发布设置：</td>
                <td style="height: 29px; text-align: left;" width="141">
        <asp:CheckBox ID="cbFB" runat="server" Text="是否发布" /></td>
                <td style="height: 29px" width="116">
        &nbsp;</td>
            </tr>
            <tr>
                <td colspan="3" style="text-align: center">
        <asp:Button ID="btnconfirm" runat="server" Text="确定" OnClick="btnconfirm_Click" />
                    <asp:Button ID="btnconcel" runat="server" Text="取消" OnClick="btnconcel_Click" /></td>
            </tr>
        </table>
    </fieldset>
    <div>
        &nbsp;</div>
    </form>
</body>
</html>
怎么编写JS判断四个选项的文本框内所输入的内容一样，因为四个选项不可能是一样的，求助啊各位