1WebView(
2              initialUrl: url,
3              javascriptMode: JavascriptMode.unrestricted,
4              javascriptChannels: Set.from([
5                JavascriptChannel(
6                    name: 'Print',
7                    onMessageReceived: (JavascriptMessage message) {
8                      //This is where you receive message from 
9                      //javascript code and handle in Flutter/Dart
10                      //like here, the message is just being printed
11                      //in Run/LogCat window of android studio
12                      print(message.message);
13                    })
14              ]),
15              onWebViewCreated: (WebViewController w) {
16                webViewController = w;
17              },
18            )
19

1<script type='text/javascript'>
2    Print.postMessage('Hello World being called from Javascript code');
3</script>
4