Support for the experimental syntax 'classProperties' isn't currently enabled (8:16). Add @babel/plugin-proposal-class-properties

问题

I'm trying to compile my React Native App and I'm getting the following error:

SyntaxError: C:\Users\Ori\Desktop\Projects\React\my-app\node_modules@react-native-community\google-signin\src\GoogleSignin.js: Support for the experimental syntax 'classProperties' isn't currently enabled (8:16)

Add @babel/plugin-proposal-class-properties (https://git.io/vb4SL) to the 'plugins' section of your Babel config to enable transformation.

If I understand correctly, since it is a react native app, the .babelrc file is ignored, but there are still some ways to overcome that. I have seen a few solutions on the web but none seem to work for me.

I've tried:

• adding babel.config.js with in the same folder as package.json:

module.exports = {
    presets: [
        '@babel/preset-env',
        '@babel/preset-react',
        '@babel/preset-typescript'
    ],
    plugins: [
        '@babel/plugin-proposal-class-properties'
    ]
};

• adding babel configuration to package.json

{
    presets: [
        '@babel/preset-env',
        '@babel/preset-react',
        '@babel/preset-typescript'
    ],
    plugins: [
        '@babel/plugin-proposal-class-properties'
    ]
}

• adding loose property to plugins:

"plugins": [
    [
      "@babel/plugin-proposal-class-properties",
      {
        "loose": true
      }
    ]
  ]

nothing seems to work.

---

My code:

package.json:

{
  "name": "my-app",
  "version": "0.1.0",
  "private": true,
  "dependencies": {
    "@material-ui/core": "^4.5.0",
    "@material-ui/icons": "^4.4.3",
    "@react-native-community/google-signin": "^3.0.1",
    "jquery": "^3.4.1",
    "react": "^16.10.2",
    "react-dom": "^16.10.2",
    "react-ga": "^2.7.0",
    "react-native-google-signin": "^2.1.0",
    "react-scripts": "3.2.0"
  },
  "scripts": {
    "start": "react-scripts start",
    "build": "react-scripts build",
    "test": "react-scripts test",
    "eject": "react-scripts eject"
  },
  "eslintConfig": {
    "extends": "react-app"
  },
  "browserslist": {
    "production": [
      ">0.2%",
      "not dead",
      "not op_mini all"
    ],
    "development": [
      "last 1 chrome version",
      "last 1 firefox version",
      "last 1 safari version"
    ]
  },
  "babel": {
    "presets": [
      "@babel/preset-env",
      "@babel/preset-react"
    ],
    "plugins": [
      [
        "@babel/plugin-proposal-class-properties",
        {
          "loose": true
        }
      ]
    ]
  },
  "devDependencies": {
    "@babel/cli": "^7.6.4",
    "@babel/core": "^7.6.4",
    "@babel/plugin-proposal-class-properties": "^7.5.5"
  }
}

babel.config.js:

module.exports = {
    plugins: [
        ['@babel/plugin-proposal-decorators', { legacy: true }],
        ['@babel/plugin-proposal-class-properties', { loose: true }],
        '@babel/plugin-syntax-dynamic-import',
        '@babel/plugin-transform-regenerator',
        [
            '@babel/plugin-transform-runtime',
            {
                helpers: false,
                regenerator: true,
            },
        ],
    ],
    presets: [
        "@babel/preset-flow",
        'module:metro-react-native-babel-preset',
    ],
};

If anyone can shine a light on the issue that would be great, Thank you!

回答1:

According to [this GitHub][1] issue if you using create-react-app you should copy your .babelrc or babel.config.js configurations to webpack.config.js and delete those.because of htis two line of code babelrc: false,configFile: false, your config in babelrc,.. are useless. and your webpack.config.js is in your ./node_madules/react-scripts/config folder. you can solve the problem like this:

{
              test: /\.(js|mjs)$/,
              exclude: /@babel(?:\/|\\{1,2})runtime/,
              loader: require.resolve('babel-loader'),
              options: {
                babelrc: false,
                configFile: false,
                compact: false,
                presets: [
                  [
                    require.resolve('babel-preset-react-app/dependencies'),
                    { helpers: true },

                  ],
                  '@babel/preset-env', '@babel/preset-react'
                ],
                plugins: ['@babel/plugin-proposal-class-properties'],
                .
                .
                .

or you can change babelrc: false,configFile: false, to true according to your config file. or you can eject and do this.

来源：https://stackoverflow.com/questions/58349305/support-for-the-experimental-syntax-classproperties-isnt-currently-enabled-8