Question

想要使用ES8异步/等待我的项目。最近一直在ReactNative上使用它与Expo，所以没想到ReactJS有任何问题。虽然，该应用程序现在无法构建... 这是我得到的错误：

    Syntax error: C:/projects/project1/src/containers/OfferOverview.js: Unexpected token (84:40)
      83 |
    > 84 |   initialGetProduct = async (productId) => {
         |                                         ^
      85 |     const { dispatch } = this.props;
      86 |     await dispatch(resetOfferStateAction());
      87 |     dispatch(getProductAction(productId));

这是组件，我已经删除了大部分内容，因为我怀疑它们可能与此问题有关：

export class OfferOverview extends Component {
  componentWillMount() {
    this.initialGetProduct(this.props.location.query.product_id);
  }

  // same error will be using async initialGetProduct() {
  initialGetProduct = async (productId) => {
    const { dispatch } = this.props;
    await dispatch(resetOfferStateAction());
    dispatch(getProductAction(productId));
    this.selectProduct(productId);
  }

  render() { ... }
}

我尝试在babel配置中设置es2017预设，与使用“transform-async-to-generator”插件相同。这就是我在.babelrc文件中的内容：

{
  "presets": [
    "es2017",
    "react",
    "stage-0"
  ],
  "plugins": [
    "react-hot-loader/babel",
    "transform-async-to-generator",
    "transform-class-properties",
    ["import", { "libraryName": "antd", "style": "css" }]
  ]
}

这是我的eslint配置。关于eslint讨论，他们说这是更多babel-eslint问题，虽然我已经添加了parserOptions ecmaVersion = 2017：

module.exports = {
  root: true,

  parser: 'babel-eslint',

  // import plugin is termporarily disabled, scroll below to see why
  plugins: [/*'import', */'flowtype', 'jsx-a11y', 'react'],

  env: {
    browser: true,
    commonjs: true,
    node: true
  },

  parserOptions: {
    ecmaVersion: 2017,
    sourceType: 'module',
    ecmaFeatures: {
      jsx: true,
      generators: true,
      experimentalObjectRestSpread: true
    }
  },

  settings: {
    'import/ignore': [
      'node_modules',
      '\\.(json|css|jpg|png|gif|eot|svg|ttf|woff|woff2|mp4|webm)$',
    ],
    'import/extensions': ['.js'],
    'import/resolver': {
      node: {
        extensions: ['.js', '.json']
      }
    }
  },

  rules: { ... }
};

并打包json依赖项：

"devDependencies": {
    "babel-cli": "^6.26.0",
    "babel-core": "^6.13.2",
    "babel-eslint": "^6.1.2",
    "babel-plugin-transform-async-to-generator": "^6.24.1",
    "babel-plugin-transform-class-properties": "^6.24.1",
    "babel-plugin-transform-runtime": "^6.12.0",
    "babel-polyfill": "^6.26.0",
    "babel-preset-es2015": "^6.13.2",
    "babel-preset-es2016": "^6.24.1",
    "babel-preset-es2017": "^6.24.1",
    "babel-preset-react": "^6.11.1",
    "babel-preset-stage-0": "^6.24.1",
    "coveralls": "^2.11.12",
    "eslint": "^3.2.2",
    "eslint-config-airbnb": "^10.0.0",
    "eslint-plugin-react": "^6.0.0",
    "ignore-styles": "^4.0.0",
    "istanbul": "^1.0.0-alpha.2",
    "mocha": "^3.0.2",
    "nock": "^8.0.0",
    "react-addons-test-utils": "^15.3.0",
    "react-scripts": "0.2.1",
    "redux-mock-store": "^1.1.2",
    "redux-saga-devtools": "^0.1.2"
},
"dependencies": {
    "babel-polyfill": "^6.26.0",
    "enzyme": "^2.4.1",
    "eslint-plugin-flowtype": "^2.39.1",
    "eslint-plugin-jsx-a11y": "^6.0.2",
    "expect": "latest",
    "isomorphic-fetch": "^2.2.1",
    "jsdom": "^9.9.1",
    "lodash": "^4.17.4",
    "nuka-carousel": "^2.3.0",
    "pushstate-server": "latest",
    "react": "^15.2.1",
    "react-dom": "^15.2.1",
    "react-redux": "^4.4.5",
    "react-router": "^2.6.0",
    "react-router-redux": "^4.0.8",
    "react-sidebar": "^2.3.2",
    "redux": "^3.6.0",
    "redux-logger": "3.0.1",
    "redux-saga": "^0.14.3"
},

会不会感谢任何可能出错的提示？

Answer 1

我没有运行代码，但您未正确声明initialGetProduct功能。应该是

async initialGetProduct() {...

Answer 2

所以这个问题与我想象的有点不同。我使用react脚本来启动我的应用程序，我的错误是我认为我在项目中的配置（我不是最初启动它的人）已被某种方式使用。但事实并非如此。因此，我必须做的就是更新react-scripts版本。它是0.2.1，现在它是^ 1.0.17，难怪它无法与ES8一起工作...... 很抱歉给所有试图帮助的人带来不便，谢谢大家，你的建议教会了我很多。在react-scripts配置中，他们只有这个用于babel：

          // Process JS with Babel.
          {
            test: /\.(js|jsx|mjs)$/,
            include: paths.appSrc,
            loader: require.resolve('babel-loader'),
            options: {
              // @remove-on-eject-begin
              babelrc: false,
              presets: [require.resolve('babel-preset-react-app')],
              // @remove-on-eject-end
              // This is a feature of `babel-loader` for webpack (not Babel itself).
              // It enables caching results in ./node_modules/.cache/babel-loader/
              // directory for faster rebuilds.
              cacheDirectory: true,
            },
          },

在带有Babel的ReactJS上使用async await会导致Error：Unexpected token

2 个答案: