Flutter_webview_js

main.dart

Please add below in ‘pubspec.yaml’： 
webview_flutter: ^0.3.5+2
oktoast: ^2.0.0


import 'dart:async';

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

void main() => runApp(MyApp());

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return OKToast(
      child: MaterialApp(
        title: 'Flutter Demo',
        theme: ThemeData(
          // This is the theme of your application.
          //
          // Try running your application with "flutter run". You'll see the
          // application has a blue toolbar. Then, without quitting the app, try
          // changing the primarySwatch below to Colors.green and then invoke
          // "hot reload" (press "r" in the console where you ran "flutter run",
          // or simply save your changes to "hot reload" in a Flutter IDE).
          // Notice that the counter didn't reset back to zero; the application
          // is not restarted.
          primarySwatch: Colors.blue,
        ),
        home: WebViewPage(),
      ),
    );
  }
}

class WebViewPage extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return WebViewPageState();
  }
}

class WebViewPageState extends State<WebViewPage> {
  JavascriptChannel _alertJavascriptChannel(BuildContext context) {
    return JavascriptChannel(
        name: 'Toast',
        onMessageReceived: (JavascriptMessage message) {
          showToast(message.message);
        });
  }

  final Completer<WebViewController> _controller =
      Completer<WebViewController>();

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('Flutter WebView example'),
      ),
      body: Builder(builder: (BuildContext context) {
        return WebView(
          initialUrl: 'http://bin.amazeui.org/ruviyabibu',
          javascriptMode: JavascriptMode.unrestricted,
          onWebViewCreated: (WebViewController webViewController) {
//            _controller = webViewController;
            _controller.complete(webViewController);
          },
          javascriptChannels: <JavascriptChannel>[
            _alertJavascriptChannel(context),
          ].toSet(),
          navigationDelegate: (NavigationRequest request) {
            if (request.url.startsWith('js://webview')) {
              showToast('JS调用了Flutter By navigationDelegate');
              print('blocking navigation to $request}');
              return NavigationDecision.prevent;
            }
            print('allowing navigation to $request');
            return NavigationDecision.navigate;
          },
          onPageFinished: (String url) {
            print('Page finished loading: $url');
          },
        );
      }),
      floatingActionButton: jsButton(),
    );
  }

  Widget jsButton() {
    return FutureBuilder<WebViewController>(
        future: _controller.future,
        builder: (BuildContext context,
            AsyncSnapshot<WebViewController> controller) {
          if (controller.hasData) {
            return FloatingActionButton(
              onPressed: () async {
                _controller.future.then((controller) {
                  controller
                      .evaluateJavascript('callJS("visible")')
                      .then((result) {});
                });
              },
              child: Text('call JS'),
            );
          }
          return Container();
        });
  }
}

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