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关于JS客户端对服务器控件赋值,Post后不能保留值的解决办法

news 来源：原创 2024/5/19 4:06:59

这个问题老早以前就发现了.但是因为是个小问题.对我的影响不大,所以也没去解决..但是这两天有几个网友在MSN上询问..索性就把解决办法贴出来.给需要的朋友..

众所周知,页面在回传后,服务器控件会保存其上次的提交是值.但是用JS在客户端动态添加的值,确在服务器回传后烟消云散.尤其是对于Select联动很不方便.给我们的工作带来了极大的不便.怎么办呢??

我的做法是:前台JS赋值后,用一个Hidden保存值,并将Hidden设置runat="server"..后台需要的时候取Hidden的值就好了.这样基本的文本控件取值问题就解决了..但是我测试Select联动的时候,发现始终不能将动态添加的JS脚本设为Selected..最后做了个变通的方法.
以下是页面的完整代码:

<% @ Page language = " c# " Codebehind = " WebForm1.aspx.cs " AutoEventWireup = " false " Inherits = " SMS.test.WebForm1 " %>
<! DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN" >
< HTML >
     < HEAD >
         < title > WebForm1 </ title >
         < meta name ="GENERATOR" Content ="Microsoft Visual Studio .NET 7.1" >
         < meta name ="CODE_LANGUAGE" Content ="C#" >
         < meta name ="vs_defaultClientScript" content ="JavaScript" >
         < meta name ="vs_targetSchema" content ="http://schemas.microsoft.com/intellisense/ie5" >
         < script language ="javascript" >
         function add(){ // 填充Select中的值
             var myList = document.all.list;
            myList.options[myList.options.length] = new Option( " 11 " , " 11 " );
            myList.options[myList.options.length] = new Option( " 22 " , " 22 " );
            myList.options[myList.options.length] = new Option( " 33 " , " 33 " );
        }

         function onchanges(){ // 对Hidden控件赋值
             var myc = document.all.list;
            document.all.hid.value = myc.options[myc.selectedIndex].value;

        }

         function sel(){ // 匹配Select中的值,并设置selected
             var myc = document.all.list;
             for (i = 0 ; i < myc.options.length;i ++ ){ // 循环匹配值

                  if (document.all.hid.value == myc.options[i].value){
                    myc.options[i].selected = true ;
                     break ;
                 }
            }
        }
         </ script >
     </ HEAD >
     < body MS_POSITIONING ="GridLayout" >
         < form id ="Form1" method ="post" runat ="server" >
             < FONT face ="宋体" >
                 < asp:Button id ="Button1" style ="Z-INDEX: 101; LEFT: 488px; POSITION: absolute; TOP: 392px" runat ="server"
                    Text ="Button" ></ asp:Button >
                 < asp:DropDownList onchange ="onchanges();" id ="list" style ="Z-INDEX: 103; LEFT: 288px; POSITION: absolute; TOP: 200px"
                    runat ="server" >
                     < asp:ListItem Value ="请选择" />
                 </ asp:DropDownList >
                 < input type ="hidden" value ="" runat ="server" id ="hid" >
                 < asp:Label id ="Label1" title ="aaaaabbbbb" style ="Z-INDEX: 102; LEFT: 304px; POSITION: absolute; TOP: 392px"
                    runat ="server" > Label </ asp:Label ></ FONT >
         </ form >
         < script language =javascript >
         add();
         sel();

         </ script >
     </ body >
</ HTML >

如果需要在后台引用.就在后台取hidden.value的值就可以了..有兴趣的朋友可以把add()放在<body>的onLoad中看看..就会产生我所说的情况了..

转载于:https://www.cnblogs.com/lixianhuei/archive/2005/08/04/207289.html