檔案上傳功能在 IE9+、Firefox、Chrome 均正常，唯獨 IE8 表現異常：檔案確實上傳至伺服器、瀏覽器狀態列顯示成功，但 `success`、`error`、`complete` 等所有回調函數均不觸發。
`jquery.form.js` 內部對檔案上傳採用隱藏 `` 模擬 AJAX。IE8 在 `iframe` 載入完成時，`document.readyState` 變化順序與標準瀏覽器不同，導致插件判斷「請求尚未完成」而不觸發回調。</p> <h2>三步排查與修復</h2> <h3>1. 使用 Fiddler/Charles 抓包確認</h3> <ul> <li>請求是否真正發出？（HTTP 200/304）</li> <li>回應標頭 `Content-Type` 是否為 `text/html` 或 `application/json`？IE8 要求回應必須為 `text/html` 且包含 `<textarea>` 包裹 JSON，否則解析失敗。</li> </ul> <h3>2. 修正伺服器端回應格式</h3> <pre><code>// Java/Spring MVC 範例 response.setContentType("text/html;charset=UTF-8"); PrintWriter out = response.getWriter(); out.write("<textarea>" + jsonString + "</textarea>"); out.flush(); </code></pre> <h3>3. 客戶端加入 `iframe` 載入兜底邏輯</h3> <pre><code>var options = { // ... 原有設定 dataType: 'json', // 期望 JSON iframe: true, // 強制 iframe 模式 iframeSrc: 'javascript:false;', // 避免 IE8 "非安全內容" 警告 success: function(responseText, statusText, xhr, $form) { // 手動解析 textarea 內容 var data = typeof responseText === 'string' ? $.parseJSON($(responseText).find('textarea').text()) : responseText; // 原有成功邏輯 handleSuccess(data); } }; $('#uploadForm').ajaxSubmit(options); </code></pre> <h2>替代方案：放棄 ajaxForm，改用原生 `FormData` + `XMLHttpRequest` Level 2</h2> <p>若專案已放棄 IE8 支援（Microsoft 2016 年停止更新），建議直接使用現代 API，程式碼更簡潔、穩定。</p> <h2>總結</h2> <p>IE8 回調失效 90% 是「回應 Content-Type 錯誤」或「iframe 事件時序」導致。調整回應為 `text/html` + `<textarea>` 包裹 JSON，並在 `success` 中手動解析，即可相容。</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/bczhwd/36095.html' >Awk 分隔符 `][` 深度解析：按 `][` 切割欄位並篩選第四欄時間範圍</a> <li>下一篇文章： <a class='LinkNextArticle' href='https://code.yunyiwangluo.com/bianchen/bczhwd/36097.html' >g++ 編譯報錯 `string is not a type`？缺少 `<string>` 標頭檔才是元兇</a> </ol> </div> </div> <div class="qirnxbd bg1 mt20"> <div class="jdbsbav"> <a href='https://code.yunyiwangluo.com/bianchen/bczhwd/' 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