addJavaScriptChannel method

Implementation

@override
Future<void> addJavaScriptChannel(
  JavaScriptChannelParams javaScriptChannelParams,
) async {
  final String channelName = javaScriptChannelParams.name;

  if (_messageChannels.containsKey(channelName)) {
    throw new ArgumentError(
      'A JavaScriptChannel with name `$channelName` already exists.',
    );
  }

  final channel = _messageChannels[channelName] = WebWebViewMessageChannel(
    name: channelName,
    params: javaScriptChannelParams,
    webChannel: web.MessageChannel(),
  );
  final completer = Completer<bool>();

  channel.webChannel.port1.onmessage = (web.MessageEvent e) {
    if (e.data.toString() == 'flutter_webwebview._connected') {
      completer.complete(true);
      channel.webChannel.port1.onmessage = (web.MessageEvent e) {
        javaScriptChannelParams.onMessageReceived(
          new JavaScriptMessage(message: e.data.toString()),
        );
      }.toJS;
    }
  }.toJS;

  if (_webWebViewParams.iFrame.contentWindow != null) {
    _connectMessageChannel(channel);

    await completer.future;
  }
}