We call webView evaluateJavaScript:javaScript completionHandler:^(id _Nullable result, NSError *_Nullable error) API to inject a javascript to WKWebView. The javascript contains "window.xxx"definition. Since iOS 15, "window.xxx" can not be found and it will return "undefined" when accessing "window.xxx" . It seems that javascript "window" object can not have any custom sub-object. However same javascript code works fine on iOS 14.x and below. Any ideas? Thanks!