An interface implemented by a webview if it supports showing native popups triggered by JavaScript dialog APIs like window.alert(), window.confirm(), and beforeunload.
await webViewPrefab.WaitUntilInitialized;
var webViewWithNativeDialogs = webViewPrefab.WebView as IWithNativeJavaScriptDialogs;
if (webViewWithNativeDialogs == null) {
    Debug.Log("This 3D WebView plugin doesn't yet support IWithNativeJavaScriptDialogs: " + webViewPrefab.WebView.PluginType);
    return;
}
webViewWithNativeDialogs.SetNativeJavaScriptDialogsEnabled(false); void SetNativeJavaScriptDialogsEnabled(bool enabled) Native JavaScript dialog popups are enabled by default but can be disabled using this method.