playground/frontend/lib/utils/javascript_post_message.dart

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import 'dart:convert';
import 'dart:html' as html;

/// Sends the [message] repeatedly 30 times with the interval of one second.
///
/// Call this to send [message] to a newly opened window when it is unknown
/// if it is interactive yet.
///
/// The receiver should be idempotent or be able to ignore repeated messages
/// after it handles the first one.
void javaScriptPostMessageRepeated(
  html.WindowBase window,
  dynamic message,
) async {
  final messageString = jsonEncode(message);

  for (int i = 30; --i >= 0; ) {
    window.postMessage(messageString, '*');
    await Future.delayed(const Duration(seconds: 1));
  }
}