內容頁面的 JavaScript 需讀取母版頁面的 HiddenField 值，但母版頁面渲染後的 ClientID 會加上命名容器前綴（如 ctl00_MainContent_HiddenField1），且若內容頁在 `` 中，需跨框架存取。</p> <h2>解決方案</h2> <pre><code><script type="text/javascript"> function Check() { // 1. 透過 <%= HiddenField1.ClientID %> 取得正確 ID // 2. 若在 iframe 中，使用 parent.document 跨框架查找 var hidden = parent.document.getElementById('<%= HiddenField1.ClientID %>'); var val = hidden ? hidden.value : ''; return confirm("您已運輸 " + val + " 台"); } </script></code></pre> <h2>關鍵點</h2> <ul> <li><code>HiddenField1.ClientID</code>：伺服器端渲染時展開為實際 HTML id，**必須在 `<%= %>` 區塊中輸出**，不可放在外部 .js 檔。</li> <li><code>parent.document</code>：內容頁若在 `<iframe>` 中，母版頁面位於父視窗，需用 `parent.document` 查找；同頁面則直接用 `document`。</li> <li>若母版頁面控制項在 `<form runat="server">` 內，ClientID 前綴通常為 `ctl00$ContentPlaceHolderID$`。</li> </ul> <h2>進階：外部 .js 檔取得 ClientID</h2> <pre><code>// 頁面內嵌腳本定義全域變數 <script> var hiddenFieldId = '<%= HiddenField1.ClientID %>'; </script> // 外部 common.js function Check() { var hidden = parent.document.getElementById(hiddenFieldId); // ... }</code></pre> <h2>現代替代方案</h2> <p>ASP.NET 4.0+ 可設定 <code>ClientIDMode="Static"</code> 讓 ClientID 等同 Server ID，或改用 `<%# HiddenField1.ClientID %>` 搭配 `Page.DataBind()`，但在母版頁面架構下，`<%= %>` 仍是最直接可靠的方式。</p> <div class="qcxs_ie_he"></div> </div> <div class="akevx_own"> <script language='javascript' src='/ad/p.js'></script></div> <div class="akevx_mj"> </div> <div class="qcxs_ie_he"></div> <ol class="qmsbvx_hsb ovv_hex"> <li>上一篇文章： <a class='LinkPrevArticle' href='https://code.yunyiwangluo.com/bianchen/aspnetjc/53698.html' >ASP.NET 資料繫結實戰：RadioButtonList、CheckBoxList、DropDownList 兩級聯動完整範例</a> <li>下一篇文章： <a class='LinkNextArticle' href='https://code.yunyiwangluo.com/bianchen/aspnetjc/53700.html' >.NET 讀取非標準組態檔：ExeConfigurationFileMap 完整範例</a> </ol> </div> </div> <div class="qirnxbd bg1 mt20"> <div class="jdbsbav"> <a href='https://code.yunyiwangluo.com/bianchen/aspnetjc/' target="_blank">ASP.NET 基礎</a> <div class="jdbsbav_hx"></div> </div> 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HiddenField
ctl00_MainContent_HiddenField1
