.babelrc

// .babelrc
{
  "presets": [
    [
      "@babel/preset-env",
      {
        "targets": {
          "browsers": [
            ">0.2%",
            "not dead",
            "not op_mini all",
            "last 2 versions",
            "ie >= 8",
            "iOS >= 8",
            "Android >= 4"
          ]
        },
        "modules": false,
        "useBuiltIns": "entry", // usage
        "corejs": 3,
        "debug": false, // 是否输出启用的plugins列表
        "spec": false, // 是否允许more spec compliant，但可能转译出的代码更慢
        "loose": true, // 是否允许生成更简单es5的代码，但可能不那么完全符合ES6语义
        "include": [], // 总是启用的 plugins
        "exclude": [],  // 强制不启用的 plugins
        "forceAllTransforms": false // 强制使用所有的plugins，用于只能支持ES5的uglify可以正确压缩代码
      }
    ],
    [
      "@babel/preset-react",
      {
        // "pragma": "dom", // default pragma is React.createElement
        // "pragmaFrag": "DomFrag", // default is React.Fragment
        "throwIfNamespace": false
      }
    ]
  ],
  "plugins": [
    ["@babel/plugin-proposal-decorators", { "legacy": true }],
    [
      // @babel/plugin-transform-runtime: 避免 polyfill 污染全局变量，减小打包体积
      "@babel/plugin-transform-runtime",
      {
        // "polyfill": false,
        "absoluteRuntime": false,
        "corejs": 3, // 对应 @babel/runtime-corejs@3，需要填3
        "helpers": false,
        "regenerator": true,
        "useESModules": false
      }
    ],
    ["@babel/plugin-syntax-dynamic-import"],
    ["@babel/plugin-transform-modules-commonjs", {
      "loose": true
    }], // This plugin transforms ES2015 modules to CommonJS
    ["@babel/plugin-transform-arrow-functions", { "spec": false }],
    ["@babel/plugin-proposal-class-properties", { "loose": true }],
    ["react-hot-loader/babel"]
  ]
}