Expo 51.0.8执行assembleRelease出现大量警告，请求技术支持

问题描述 #

使用Expo 51.0.8执行./gradlew assembleRelease构建Release包时，触发大量警告，核心类型包括：

• 全局变量未声明（如URL、fetch、Promise等浏览器/React Native全局对象）
• Direct call to eval(), but lexical scope is not supported代码执行警告

关键构建日志片段：

./gradlew assembleRelease

Configure project :expo
Using expo modules

• expo-asset (10.0.6)
• expo-constants (16.0.1)
• expo-file-system (17.0.1)
• expo-font (12.0.5)
• expo-keep-awake (13.0.2)
• expo-linear-gradient (13.0.2)
• expo-modules-core (1.12.11)
• expo-splash-screen (0.27.4)
• expo-sqlite (14.0.3)
• expo-system-ui (3.0.4)
• expo-web-browser (13.0.3)

Configure project :react-native-reanimated
Android gradle plugin: 8.2.1
Gradle: 8.6

Task :app:createBundleReleaseJsAndAssets
warning: Bundler cache is empty, rebuilding (this may take a minute)
Writing bundle output to: android\app\build\generated\assets\createBundleReleaseJsAndAssets\index.android.bundle
...
android\app\build\generated\assets\createBundleReleaseJsAndAssets\index.android.bundle:763:63: warning: Direct call to eval(), but lexical scope is not supported.
...typeof expo === "undefined" ? eval("require") : function (moduleId) {
^~~~~~~~~~~~~~~
android\app\build\generated\assets\createBundleReleaseJsAndAssets\index.android.bundle:843:24: warning: the variable "URL" was not declared in function "_fetch"
props[0] = new URL(props[0], window.location?.origin).toString();
^~~
...（其余警告略）

解决方案 #

1. 声明全局变量消除未定义警告 #

这类警告源于Babel未识别React Native/Expo内置的全局对象，通过Babel配置显式声明即可解决：

• 确保已安装@babel/plugin-transform-runtime
• 修改项目根目录babel.config.js，添加全局变量映射：

module.exports = function(api) {
  api.cache(true);
  return {
    presets: ['babel-preset-expo'],
    plugins: [
      [
        '@babel/plugin-transform-runtime',
        {
          globals: {
            'URL': true,
            'fetch': true,
            'Promise': true,
            'setImmediate': true,
            'setTimeout': true,
            'clearTimeout': true,
            'Headers': true,
            'Request': true,
            'Response': true,
            'FileReader': true,
            'Blob': true,
            'FormData': true,
            'URLSearchParams': true,
            'AbortController': true,
            'XMLHttpRequest': true,
            'self': true,
            'performance': true,
            'navigator': true,
            'MessageChannel': true,
            'requestAnimationFrame': true,
            'cancelAnimationFrame': true,
            'location': true,
            'queueMicrotask': true,
            'structuredClone': true,
            'document': true,
            'HTMLElement': true,
            'MutationObserver': true,
            'getComputedStyle': true,
            'SharedArrayBuffer': true
          }
        }
      ]
    ]
  };
};

2. 抑制eval相关警告 #

eval警告多来自Reanimated等库的worklet代码，通过Metro配置压缩器忽略该类警告：

• 修改metro.config.js：

const { getDefaultConfig } = require('expo/metro-config');

const config = getDefaultConfig(__dirname);

config.transformer.minifierConfig = {
  compress: {
    drop_console: true,
    warnings: false,
    pure_funcs: ['eval'] // 标记eval为纯函数，消除警告
  },
  mangle: {
    keep_fnames: true
  }
};

module.exports = config;

• 确保Reanimated版本与Expo 51兼容，建议升级到~3.10.1

3. 清理缓存重新构建 #

旧缓存可能导致配置不生效，执行以下命令彻底清理后重新构建：

npx expo start --clear
cd android && ./gradlew clean && ./gradlew assembleRelease

4. 移除冗余测试代码 #

日志中出现jest相关警告，检查项目中是否残留测试文件或配置，移除Release构建不需要的测试代码。

验证 #

重新执行./gradlew assembleRelease，确认警告数量减少或完全消失，成功生成Release安装包。

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