test:

src/jensen.js

@@ -695,17 +695,17 @@ Jensen.prototype.getFile = async function (filename, length, ondata, onprogress)
     let fname = [];
     for (let i = 0; i < filename.length; i++) fname.push(filename.charCodeAt(i));
 
-    // function visibilitychange() {
-    //     if (document.visibilityState === 'hidden') {
-    //         console.log('Page is hidden');
-    //         // 可以选择暂停数据传输，或通过 Web Worker 继续后台任务
-    //     } else {
-    //         console.log('Page is visible');
-    //         // 重新开始或恢复数据传输
-    //     }
-    // }
-    //
-    // document.addEventListener('visibilitychange', visibilitychange);
+    function visibilitychange() {
+        if (document.visibilityState === 'hidden') {
+            console.log('Page is hidden');
+            // 可以选择暂停数据传输，或通过 Web Worker 继续后台任务
+        } else {
+            console.log('Page is visible');
+            // 重新开始或恢复数据传输
+        }
+    }
+
+    document.addEventListener('visibilitychange', visibilitychange);
 
     let flen = 0;
     let handler = (msg) => {