SyntaxError in Webpack / React.js Unexpected token = { } in React

Question

In one of my .js file, I'm getting the following error from Webpack:

  4 | export default function(ComposedComponent) {
  5 |   class Authentication extends Component {
> 6 |     static contextTypes = {
    |                         ^
  7 |       router: React.PropTypes.object
  8 |     }
  9 |

These are my devdependencies:

  "devDependencies": {
    "babel-core": "^6.17.0",
    "babel-loader": "^6.2.0",
    "babel-plugin-transform-object-rest-spread": "^6.26.0",
    "babel-preset-env": "^1.6.0",
    "babel-preset-react": "^6.16.0",
    "babel-preset-stage-3": "^6.24.1",
    "css-loader": "^0.26.1",
    "file-loader": "^1.1.4",
    "html-webpack-plugin": "^2.30.1",
    "image-webpack-loader": "^3.4.2",
    "rimraf": "^2.6.2",
    "style-loader": "^0.13.1",
    "url-loader": "^0.5.9",
    "webpack": "2.2.0-rc.0",
    "webpack-dev-server": "^2.2.0-rc.0"
  }

And this is my Webpack configuration:

{
  "presets": ["env", "react", "stage-3"],
  "plugins": ["transform-object-rest-spread"]
}

Could anybody tell which plugin or package is missing? Thank you!

Please look at this and this. You just need to add correct babel presets to be able to use static class properties. — Abhishek Ghosh
– Abhishek Ghosh, Commented Oct 2, 2017 at 21:34

Daniel · Accepted Answer · 2017-10-02 20:15:56Z

1

Nothing is missing, it's just incorrect syntax.

Static methods should be (as the name implies) functions.

Try:

class Authentication extends Component {
   ...
}

Authentication.contextTypes = {
    router: React.PropTypes.object
}

answered Oct 2, 2017 at 20:15

Daniel

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4 Comments

TheGabornator Over a year ago

Same issue... Now, it's pointing to the . between the Authentication.contextTypes. Interestingly, it was OK with the old setup when I downloaded the tutorial, it's just not working with my new Webpack transpiler.

Daniel Over a year ago

Longshot but try babel-preset-es2015 and add es2015 to your presets

Abhishek Ghosh Over a year ago

@Daniel is right. You just have to add correct presets. Look at my comment for links.

TheGabornator Over a year ago

Thank you for your efforts, but I just keep getting error messages. This time is Uncaught Error: _registerComponent(...): Target container is not a DOM element - even thought the script is at the documents bottom. :(

Aymeric Bouzy aybbyk · Accepted Answer · 2017-10-03 07:39:11Z

1

Class properties is a stage 2 proposal at the moment, so it's not included in babel-preset-env. You can either:

include only this specific transform with .babelrc:

{ "plugins": ["transform-class-properties"] }
include all stage 2 proposals with :

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

Please consider the risks before adding all stage-2 proposals : https://babeljs.io/docs/plugins/preset-stage-2/

answered Oct 3, 2017 at 7:39

Aymeric Bouzy aybbyk

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