var nameValue=$("#"+name+"DelFlag_"+id).attr("name"); 中的nameValue是一个字符串！并非boolean值

困惑了两天的js，今天早上终于搞定了！

现在直接来正题....

先看看效果图：

下面是一个jsp..

  1 <%@ page language="java" contentType="text/html; charset=UTF-8" pageEncoding="UTF-8"%>
  2 <%@ taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>
  3 <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
  4 <html xmlns="http://www.w3.org/1999/xhtml">
  5 <head>
  6 <meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
  7 <title>无标题文档</title>
  8 <link rel="stylesheet" href="${pageContext.request.contextPath}/css/admin/user/admin-userUI.css" charset="UTF-8" />
  9 <script type="text/javascript" src="${pageContext.request.contextPath}/libs/My97DatePicker/WdatePicker.js" charset="UTF-8"></script>
 10 </head>
 11 
 12 <body>
 13   <table width="100%" border="0" align="center" cellpadding="0" cellspacing="0">
 14     <tr>
 15       <td height="30">
 16         <table width="100%" border="0" cellspacing="0" cellpadding="0">
 17           <tr>
 18             <td width="15" height="30"><img src="${pageContext.request.contextPath}/img/admin/backstage-img/tab_03.gif" width="15" height="30" /></td>
 19             <td width="1101" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_05.gif"><img src="${pageContext.request.contextPath}/img/admin/backstage-img/311.gif" width="16" height="16" /> <span class="STYLE4">角色信息列表</span></td>
 20             <td width="281" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_05.gif"></td>
 21             <td width="14"><img src="${pageContext.request.contextPath}/img/admin/backstage-img/tab_07.gif" width="14" height="30" /></td>
 22           </tr>
 23         </table>
 24       </td>
 25     </tr>
 26     <tr>
 27       <td>
 28         <table width="100%" border="0" cellspacing="0" cellpadding="0">
 29           <tr>
 30             <td width="9" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_12.gif">&nbsp;</td>
 31             <td bgcolor="#f3ffe3">
 32               <table width="99%" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#c0de98" onmouseover="changeto()" onmouseout="changeback()">
 33                 <tr>
 34                   <td width="8%" height="18" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_14.gif" class="STYLE1">
 35                     <div align="center" class="STYLE2 STYLE1">
 36                      <form id="searchRoleForm" action="${pageContext.request.contextPath}/admin_role/admin-roleSearchList" method="post">
 37                                                                         名称: <input type="text" id="searchValueId" name="role.name" style=" 200px;" /> 
 38                             <input type="submit" id="roleSearchButton"  value="搜索管理员" />
 39                       </form>
 40                     </div>
 41                   </td>
 42                 </tr>
 43               </table>
 44             </td>
 45             <td width="9" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_16.gif">&nbsp;</td>
 46           </tr>
 47         </table>
 48       </td>
 49     </tr>
 50     <tr>
 51       <td>
 52         <table width="100%" border="0" cellspacing="0" cellpadding="0">
 53           <tr>
 54             <td width="9" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_12.gif">&nbsp;</td>
 55             <td bgcolor="#f3ffe3"><table width="99%" border="0" align="center" cellpadding="0" cellspacing="1" bgcolor="#c0de98" onmouseover="changeto()" onmouseout="changeback()">
 56                 <tr>
 57                   <td width="8%" height="18" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_14.gif" class="STYLE1"><div align="center" class="STYLE2 STYLE1">序号</div></td>
 58                   <td width="8%" height="18" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_14.gif" class="STYLE1"><div align="center" class="STYLE2 STYLE1">名称</div></td>
 59                   <td width="8%" height="18" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_14.gif" class="STYLE1"><div align="center" class="STYLE2 STYLE1">注册时间</div></td>
 60                   <td width="8%" height="18" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_14.gif" class="STYLE1"><div align="center" class="STYLE2 STYLE1">状态</div></td>
 61                   <td width="8%" height="18" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_14.gif" class="STYLE1"><div align="center" class="STYLE2 STYLE1">操作</div></td>
 62                 </tr>
 63                 <c:choose>
 64                   <c:when test="${empty qr.results }">
 65                     <tr>
 66                       <td height="18" bgcolor="#FFFFFF" class="STYLE2"><div align="center" class="STYLE2 STYLE1">当前没有纪录</div></td>
 67                     </tr>
 68                   </c:when>
 69                   <c:otherwise>
 70                     <c:forEach items="${qr.results }" var="role">
 71                       <tr>
 72                         <td height="18" bgcolor="#FFFFFF" class="STYLE2"><div align="center" class="STYLE2 STYLE1">${role.id }</div></td>
 73                         <td height="18" bgcolor="#FFFFFF" class="STYLE2"><div align="center" class="STYLE2 STYLE1">${role.name }</div></td>
 74                         <td height="18" bgcolor="#FFFFFF"><div align="center" class="STYLE2 STYLE1">${role.registTime }</div></td>
 75                         <td height="18" bgcolor="#FFFFFF"><div align="center"><span class="STYLE2"><img id="roleDelFlag_${role.id }" name="${role.delFlag}" src="${pageContext.request.contextPath}/img/admin/backstage-img/${role.delFlag ? '010.gif' : '005.gif' }" width="9" height="9" /></span></div></td>
 76                         <td height="18" bgcolor="#FFFFFF"><div align="center"><span class="STYLE1">[</span><a href="${pageContext.request.contextPath}/admin_role/admin-roleUpdateUI?role.id=${role.id}">资料</a><span class="STYLE1">]|</span><span class="STYLE1">[</span><a id="roleDelFlagChange_${role.id }" href="javascript:void(0);" onclick="roleDelFlagChange(${role.id},'role');">${role.delFlag ? "启用" : "<font color='red'>禁用</font>" }</a><span class="STYLE1">]</span></div></td>
 77                       </tr>
 78                     </c:forEach>
 79                   </c:otherwise>
 80                 </c:choose>
 81               </table></td>
 82             <td width="9" background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_16.gif">&nbsp;</td>
 83           </tr>
 84         </table>
 85        </td>
 86     </tr>
 87     <tr>
 88       <td height="29"><table width="100%" border="0" cellspacing="0" cellpadding="0">
 89           <tr>
 90             <td width="15" height="29"><img src="${pageContext.request.contextPath}/img/admin/backstage-img/tab_20.gif" width="15" height="29" /></td>
 91             <td background="${pageContext.request.contextPath}/img/admin/backstage-img/tab_21.gif"><table width="100%" border="0" cellspacing="0" cellpadding="0">
 92                 <tr>
 93                   <td width="25%" height="29" nowrap="nowrap"><span class="STYLE1">共<c:out value="${qr.count }" default="0"></c:out>条纪录 </span></td>
 94                   <td width="75%" valign="top" class="STYLE1"></td>
 95                 </tr>
 96               </table></td>
 97             <td width="14"><img src="${pageContext.request.contextPath}/img/admin/backstage-img/tab_22.gif" width="14" height="29" /></td>
 98           </tr>
 99         </table></td>
100     </tr>
101   </table>
102   <input type="hidden"  id="basePath" value="${pageContext.request.contextPath}"/>
103 
104   <script type="text/javascript" src="${pageContext.request.contextPath}/js/share/jquery-1.7.0.min.js" charset="UTF-8"></script>
105   <script type="text/javascript" src="${pageContext.request.contextPath}/js/admin/admin-public.js" charset="UTF-8"></script>
106   <script type="text/javascript">
107       function roleDelFlagChange(id,name){
108           var nameValue=$("#"+name+"DelFlag_"+id).attr("name");
109           if(id != "" || null != id){
110               var basePath=$("#basePath").val();
111               $.post("admin_"+name+"/admin-"+name+"DelFlagChange",{
112                   "role.id" : id
113               },function(data){
114                   if(data=="success"){
115                       if(nameValue == "true"){
116                           $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/005.gif");
117                           $("#"+name+"DelFlagChange_"+id).html("<font color='red'>禁用</font>");
118                           $("#"+name+"DelFlag_"+id).attr("name","false");
119                       }else if(nameVlue == "false"){
120                         $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/010.gif");
121                         $("#"+name+"DelFlagChange_"+id).html("启用");
122                           $("#"+name+"DelFlag_"+id).attr("name","true");
123                       }
124                   }    
125               });
126           }
127       };
128   </script>
129 </body>
130 </html>

在代码的第75,76行：

1  <td height="18" bgcolor="#FFFFFF"><div align="center"><span class="STYLE2"><img id="roleDelFlag_${role.id }" name="${role.delFlag}" src="${pageContext.request.contextPath}/img/admin/backstage-img/${role.delFlag ? '010.gif' : '005.gif' }" width="9" height="9" /></span></div></td>
2                         <td height="18" bgcolor="#FFFFFF"><div align="center"><span class="STYLE1">[</span><a href="${pageContext.request.contextPath}/admin_role/admin-roleUpdateUI?role.id=${role.id}">资料</a><span class="STYLE1">]|</span><span class="STYLE1">[</span><a id="roleDelFlagChange_${role.id }" href="javascript:void(0);" onclick="roleDelFlagChange(${role.id},'role');">${role.delFlag ? "启用" : "<font color='red'>禁用</font>" }</a><span class="STYLE1">]</span></div></td>
3

图片img的id,name为下面所示：

1 id=roleDelFlag_${role.id }  name=${role.delFlag }

说明：delFlag是role对象的一个属性，类型为boolean。

在调用的js中：

 1 <script type="text/javascript">
 2       function roleDelFlagChange(id,name){
 3           var nameValue=$("#"+name+"DelFlag_"+id).attr("name");
 4           if(id != "" || null != id){
 5               var basePath=$("#basePath").val();
 6               $.post("admin_"+name+"/admin-"+name+"DelFlagChange",{
 7                   "role.id" : id
 8               },function(data){
 9                   if(data=="success"){
10                       if(nameValue == "true"){
11                           $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/005.gif");
12                           $("#"+name+"DelFlagChange_"+id).html("<font color='red'>禁用</font>");
13                           $("#"+name+"DelFlag_"+id).attr("name","false");
14                       }else if(nameVlue == "false"){
15                         $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/010.gif");
16                         $("#"+name+"DelFlagChange_"+id).html("启用");
17                           $("#"+name+"DelFlag_"+id).attr("name","true");
18                       }
19                   }    
20               });
21           }
22       };
23   </script>

代码的第3行：

1  var nameValue=$("#"+name+"DelFlag_"+id).attr("name");

中nameValue是一个字符串！并非boolean值，所以大家看到：

1 if(nameValue == "true"){
2                           $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/005.gif");
3                           $("#"+name+"DelFlagChange_"+id).html("<font color='red'>禁用</font>");
4                           $("#"+name+"DelFlag_"+id).attr("name","false");
5                       }else if(nameVlue == "false"){
6                         $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/010.gif");
7                         $("#"+name+"DelFlagChange_"+id).html("启用");
8                           $("#"+name+"DelFlag_"+id).attr("name","true");
9                       }

第1行和第5行判断的是nameValue这个字符串是否为"true","false",

如果我们使用：

1 if(nameValue){
2                           $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/005.gif");
3                           $("#"+name+"DelFlagChange_"+id).html("<font color='red'>禁用</font>");
4                           $("#"+name+"DelFlag_"+id).attr("name","false");
5                       }else {
6                         $("#"+name+"DelFlag_"+id).attr("src",basePath+"/img/admin/backstage-img/010.gif");
7                         $("#"+name+"DelFlagChange_"+id).html("启用");
8                           $("#"+name+"DelFlag_"+id).attr("name","true");
9                       }

这样第1行，判断的是nameValue是一个对象。

相关阅读:
python常用模块②
python常用模块①
面向对象相关部分双下划线方法补充
 面向对象进阶上
 面向对象初识④
面向对象初识③
综合架构-负载均衡
 wecent 搭建
 综合架构--存储
 综合架构--备份
原文地址：https://www.cnblogs.com/hongten/p/java_javascript_var.html