KeepAlive mixin + WebView

main.dart

import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';

void main() => runApp(MaterialApp(home: MyApp()));

class MyApp extends StatefulWidget {
  @override
  _MyAppState createState() => _MyAppState();
}

class _MyAppState extends State<MyApp> {
  Key _key(int index) => Key(index.toString());

  @override
  Widget build(BuildContext context) => Scaffold(
    body:  ListView(
      children: List<Widget>.generate(
      5, (i) =>  WebViewKeepAlive(key:_key(i))),
    ),
  );
}

class WebViewKeepAlive extends StatefulWidget {
  final Key key;
  WebViewKeepAlive({this.key});

  @override
  _WebViewKeepAlive createState() => _WebViewKeepAlive();
}

class _WebViewKeepAlive extends State<WebViewKeepAlive> with AutomaticKeepAliveClientMixin {
  WebView _webView;

  @override
  bool get wantKeepAlive => true;
  
  @override
  void initState() {
    super.initState();
     _webView = WebView(
      initialUrl: "https://www.google.com/",
      javascriptMode: JavascriptMode.unrestricted,
    );
    print('init'+widget.key.toString());
  }
  @override
  void dispose() {
    super.dispose();
    _webView = null;
    print('dispose'+widget.key.toString());
  }

  @override
  Widget build(BuildContext context) {
      super.build(context);
      return Container(
      height: 400,
      child: _webView,
    );
  }
}