javascript - React 组件 render 方法中的语法错误

Question

React 组件中的render 方法如下所示:

render() {
        return <h1>Hello, {this.props.name}</h1>;
}

错误是这样的:

Module build failed (from ./node_modules/babel-loader/lib/index.js):
              SyntaxError: Unexpected token    20 |    21 |     render() { > 22
              |         return <h1>Hello, {this.props.name}</h1>;
              |      

这是我的package.json:

{
  "name": "test",
  "version": "1.0.0",
  "description": "",
  "main": "webpack.config.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "build": "webpack",
    "babel-version": "babel --version"
  },
  "babel": {
    "presets": [
       "env",
       "react",
       "stage-2"
    ]
  },
  "author": "",
  "license": "ISC",
  "devDependencies": {
    "ajv": "^6.0.0",
    "babel": "^6.23.0",
    "babel-cli": "^6.26.0",
    "babel-core": "^6.26.3",
    "babel-loader": "^7.1.5",
    "babel-plugin-transform-class-properties": "^6.24.1",
    "babel-preset-env": "^1.7.0",
    "babel-preset-react": "^6.24.1",
    "css-loader": "^1.0.0",
    "less": "^3.8.0",
    "less-loader": "^4.1.0",
    "react": "^16.4.1",
    "react-dom": "^16.4.1",
    "reactstrap": "^6.3.1",
    "style-loader": "^0.21.0",
    "webpack": "^4.16.3",
    "webpack-command": "^0.4.1"
  },
  "dependencies": {
    "bootstrap": "^4.1.3",
    "npm": "^6.3.0"
  }
}

这是全类:

export default class SearchForm extends React.Component {
    constructor(props) {
        super(props);
        this.state = {
            name: ""
        };      
    }

    handleNameChange = (e) => {
        this.setState({ name: e.target.value });
    };

    render() {
        return <h1>Hello, {this.props.name}</h1>;
    }
}

请注意，该类目前在功能方面没有意义，因为我一直在尝试找出语法错误。

我还有一个 .babelrc:

{
  "plugins": [
    ["transform-class-properties"]
  ]
}

该方法非常简单，所以我看不出问题所在。感谢任何见解。

Answer 1

您最有可能收到错误，因为上面的类属性 (handleNameChange = (e) => { ... };) 是一个 stage 2 proposal .

如果你安装了 babel-preset-stage-2 并将它添加到你的 .babelrc 错误应该得到解决。

.babelrc

{
  "presets": [
    ["env", "react", "stage-2"]
  ]
}