Syntax Error in React Component render Method

Question

The render method in the React component looks like this:

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

The error is this:

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>;
              |

Here is my 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"
  }
}

Here is the whole class:

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>;
    }
}

Note the class doesn't make sense in terms of functionality at the moment because I've been experimenting to figure out the syntax error.

I have a .babelrc also:

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

The method is pretty straightforward, so I can't see what the issue is. Any insight is appreciated.

I feel like there's an error with your class syntax not your JSX. Could you put your whole class? — MinusFour
– MinusFour, Commented Aug 3, 2018 at 23:59
Class properties (handleNameChange = (e) => { ... };) is a stage 2 proposal, so you most likely have to use "presets": [ "env", "react", "stage-2" ] — Tholle
– Tholle, Commented Aug 4, 2018 at 0:13
I think you shouldn't have the trailing semi colon after handleNameChange. — Evan Trimboli
– Evan Trimboli, Commented Aug 4, 2018 at 0:14
@EvanTrimboli That is perfectly valid, and often recommended. — Tholle
– Tholle, Commented Aug 4, 2018 at 0:15

Tholle · Accepted Answer · 2018-08-04 00:56:03Z

1

You are most likely getting the error because the class property above (handleNameChange = (e) => { ... };) is a stage 2 proposal.

If you install babel-preset-stage-2 and add it to your .babelrc the error should be resolved.

.babelrc

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

answered Aug 4, 2018 at 0:56

Tholle

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5 Comments

Vidya Over a year ago

Aren't these presets in .babelrc deprecated? Is there a more durable solution?

Tholle Over a year ago

@Vidya I'm not sure I would use the word deprecated. The entire preset system is getting redone for Babel 7, but to my knowledge there is no alternative yet for Babel 6.

Vidya Over a year ago

Ahh OK. Thanks.

SamVK Over a year ago

@Vidya Stage presets are being deprecated in Babel 7. The alternative is to simply include the all plugins those presets come with - or more specifically, only the plugins you need. (So in this case, if all you need is babel-plugin-transform-class-properties you'd just include that.) See github.com/babel/babel/blob/…

Vidya Over a year ago

That plugin was already included from the beginning. If I have babel-plugin-transform-class-properties and babel-preset-stage-2 and factor the .babelrc presets out into package.json, things fail again. I have to say that modern JS engineering is tougher than I expected. I can see why TypeScript, Reason, and Elm are so compelling.

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