错误：缺少 class 属性转换

Question

Error: Missing class properties transform

Test.js :

export class Test extends Component {
  constructor (props) {
    super(props)
  }

  static contextTypes = {
    router: React.PropTypes.object.isRequired
  }

.babelrc :

{
  "presets": ["es2015", "react", "stage-0"],
  "plugins": ["transform-class-properties"]
}

package.json :

"babel-core": "^6.5.1",
"babel-eslint": "^4.1.8",
"babel-loader": "^6.2.2",
"babel-plugin-react-transform": "^2.0.0",
"babel-plugin-transform-class-properties": "^6.5.2",
"babel-preset-es2015": "^6.5.0",
"babel-preset-react": "^6.5.0",
"babel-preset-stage-0": "^6.5.0",
"babel-register": "^6.5.2",

I have scoured the web and all fixes revolve around: Upgrading to babel6, switching the order of "stage-0" to be after "es2015". All of which I have done.

Answer 1

You need to install babel-plugin-transform-class-properties :

npm install babel-plugin-transform-class-properties --save-dev

or

yarn add babel-plugin-transform-class-properties --dev

and add the following to your Babel configuration file - usually .babelrc or babel.config.js .

"plugins": ["@babel/plugin-proposal-class-properties"],

Answer 2

OK, finally figured this out, in my webpack.config.js I had:

module: {
    loaders: [
      {
        test: /\.js?$/,
        exclude: /(node_modules|bower_components)/,
        loaders: [
          'react-hot',
          'babel?presets[]=react,presets[]=es2015,presets[]=stage-0'
        ]
      }
    ]
  }

'babel?presets[]=stage-0,presets[]=react,presets[]=es2015'

Has to be treated in the same way as .babelrc , switched stage-0 to be after es2015 and it compiles perfectly.

Answer 3

Just in case anybody is actually still facing the same issue, The following blog post did help me: https://devblogs.microsoft.com/typescript/typescript-and-babel-7/

In my case (babel 7.9.6, typescript 3.9.2, webpack 4.43.0) I had to do the following:

1. Run the following command:

    npm install --save-dev @babel/preset-typescript @babel/preset-env @babel/plugin-proposal-class-properties @babel/plugin-proposal-object-rest-spread

2. Create .babelrc file (yes, I didn't have one before and it did work just fine) with the following content:

    { "presets": [ "@babel/env", "@babel/preset-typescript" ], "plugins": [ "@babel/proposal-class-properties", "@babel/proposal-object-rest-spread" ] }

Answer 4

I had this same error and I ordered my plugins correctly in my .babelrc but it still persisted. Removing the preset parameters I defined in my webpack loader fixed it.

Former webpack config:

module: {
  rules: [
    {
      test: /.jsx?$/,
      loader: 'babel-loader',
      include: path.join(__dirname, 'src'),
      exclude: /node_modules/,
      query: {
        presets: ['es2015', 'react']
      }
    }
  ]
}

Working webpack config:

module: {
  rules: [
    {
      test: /.jsx?$/,
      loader: 'babel-loader',
      include: path.join(__dirname, 'src'),
      exclude: /node_modules/
    }
  ]
}

Answer 5

I ran into this issue when I put some arrow functions into one of my classes without thinking. Once I changed the arrow functions to regular function/method definitions the error was resolved.

Answer 6

我有这个错误，因为我使用的是stage-3而不是stage-0 。

Answer 7

The fix in my case was defining 'transform-class-properties' plugin in the options attribute of my webpack.config.js , i'm using babel V6

 rules:[
    .....,
    {
       test: /\.(js|jsx)$/,
       exclude: /(node_modules|bower_components)/,
       loader: 'babel-loader',
       options: { plugins: ['transform-class-properties']}
    }
 ]

Answer 8

由于使用了 env 预设，我也遇到了这个错误"presets": [ "react", "es2015", "stage-0", ["env", { "modules": false }]],在我之后删除 env 预设，效果很好

Answer 9

@speak is right, but you need to change the order

 loaders: [ 'react-hot', 'babel?presets[]=react,presets[]=es2015,presets[]=stage-0' ]

Answer 10

I met the same problem using koa-react-view . Get inspired by these answers and finally fixed it with the following code in the koa server.js :

 const register = require('babel-register'); register({ presets: ['es2015', 'react', 'stage-0'], extensions: ['.jsx'] });

Answer 11

Finally discovered, To remove this error in Laravel-Mix project, add below code in webpack.mix.js

mix.webpackConfig({
        module: {
            rules: [
                {
                    test: /\.js?$/,
                    exclude: /(node_modules|bower_components)/,
                    loaders: [
                        'babel-loader?presets[]=react,presets[]=es2015,presets[]=stage-0'
                    ]
                }
            ],
        }
});

Answer 12

If you are using Babel 7.4 or newer, @babel/pollify is deprecated.

Install core-js , regenerator-runtime , @babel/plugin-proposal-class-properties and babel-plugin-transform-class-properties packages.

yarn add core-js regenerator-runtime @babel/plugin-proposal-class-properties babel-plugin-transform-class-properties --dev
// or
npm install core-js regenerator-runtime @babel/plugin-proposal-class-properties babel-plugin-transform-class-properties --save-dev

Then, add to .babelrc or babel.config.js

"plugins": ["@babel/plugin-proposal-class-properties"],

Finally, add this lines in your main js file:

import "core-js/stable";
import "regenerator-runtime/runtime";

Taked from: https://stackoverflow.com/a/54490329/9481448

Answer 13

Complete working solution --

1. Use "react-pdf": "^5.7.2" version

2. import { Document, Page, pdfjs } from "react-pdf";

3. Also add this inside your functional component

useEffect(() => { pdfjs.GlobalWorkerOptions.workerSrc = https://cdnjs.cloudflare.com/ajax/libs/pdf.js/${pdfjs.version}/pdf.worker.js ;});