Flutter升级后index.html废弃警告的解决方法咨询

针对你遇到的两个废弃警告，以下是具体的修复步骤和修改后的代码示例：

1. 使用{{flutter_service_worker_version}}替换serviceWorkerVersion变量 #

• 删除原代码中定义serviceWorkerVersion的整个script块：

  <script>
    // The value below is injected by flutter build, do not touch.
    const serviceWorkerVersion = null;
  </script>
  

• 在引用该变量的位置，直接用模板令牌{{flutter_service_worker_version}}替换原变量名。

2. 升级loadEntrypoint为load方法 #

FlutterLoader.load方法简化了初始化流程，无需嵌套回调，直接通过Promise链完成引擎初始化和应用启动：

• 将原_flutter.loader.loadEntrypoint调用替换为_flutter.loader.load
• 调整参数结构，移除onEntrypointLoaded回调，改为直接链式调用initializeEngine()和runApp()

修改后的完整index.html代码 #

<!DOCTYPE html>
<html>
<head>
  <!--
    If you are serving your web app in a path other than the root, change the
    href value below to reflect the base path you are serving from.

    The path provided below has to start and end with a slash "/" in order for
    it to work correctly.

    For more details:
    * https://developer.mozilla.org/en-US/docs/Web/HTML/Element/base

    This is a placeholder for base href that will be replaced by the value of
    the `--base-href` argument provided to `flutter build`.
  -->
  <base href="$FLUTTER_BASE_HREF">

  <meta charset="UTF-8">
  <meta content="IE=Edge" http-equiv="X-UA-Compatible">
  <meta name="description" content="chapter 04">

  <!-- iOS meta tags & icons -->
  <meta name="apple-mobile-web-app-capable" content="yes">
  <meta name="apple-mobile-web-app-status-bar-style" content="black">
  <meta name="apple-mobile-web-app-title" content="flutter_layout">
  <link rel="apple-touch-icon" href="icons/Icon-192.png">

  <!-- Favicon -->
  <link rel="icon" type="image/png" href="favicon.png"/>

  <title>flutter_layout</title>
  <link rel="manifest" href="manifest.json">

  <!-- This script adds the flutter initialization JS code -->
  <script src="flutter.js" defer></script>
</head>
<body>
  <script>
    window.addEventListener('load', function(ev) {
      // Download main.dart.js
      _flutter.loader.load({
        serviceWorker: {
          serviceWorkerVersion: "{{flutter_service_worker_version}}",
        }
      }).then(function(engineInitializer) {
        return engineInitializer.initializeEngine();
      }).then(function(appRunner) {
        appRunner.runApp();
      });
    });
  </script>
</body>
</html>

内容的提问来源于stack exchange，提问作者user3523406