title: Get Json response when Webview redirect to another page in Flutter
body: <p><a href="https://pub.dev/packages/flutter_webview_plugin" rel="nofollow noreferrer">flutter_webview_plugin^0.3.11</a>
  I am building a payment gateway and in 3d secure mode I need to use Webview. Launch Webview with a response in type of html string.</p>
  <pre><code>   return Scaffold(
    body: WebviewScaffold(
      withJavascript: true,
      key: _scaffoldKey,
      url: new Uri.dataFromString(widget.d3sc, mimeType: 'text/html').toString(),
    ),
  );
  </code></pre>
  <p>It prints on the screen the security code phase. When I submit the code it redirects automatically to callback url and I can not manage to connect or get response from this url. I need to get response when code is submitted and page is redirected for having token for closing 3d secure payment. Any idea or solution ?</p>
  <p><em>Tried below code. Although it prints the redirected url, there is no json response in response element.</em></p>
  <pre><code> webView.launch(new Uri.dataFromString(widget.d3sc, mimeType: 'text/html').toString() ,withJavascript: true, withLocalStorage: true);
    webView.show();
  
    webView.onUrlChanged.listen((String event) async {
      print(&quot;${event} even eevent&quot;);
      setState(() {
        webView
            .evalJavascript(&quot;document.documentElement.innerText&quot;)
            .then((response) =&gt; print(&quot;$response response response &quot;));
  
      });
    });
  </code></pre>