"loose": true is not fix 对实验性语法 'classProperties' 的支持当前未启用

Question

目前不支持实验性语法“classProperties” 启用

我尝试了解决方案，重新构建后仍然出现错误。

Support for the experimental syntax 'classProperties' isn't currently enabled

package.json

{
  "name": "blahmodule",
  "version": "1.0.0",
  "description": "a fetch module for our project",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "build": "./node_modules/.bin/babel src --out-file index.js"
  },
  "peerDependencies": {
    "react": "^16.6.6",
    "react-dom": "^16.6.3",
    "axios": "^0.19.0"
  },
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@babel/cli": "^7.4.4",
    "@babel/core": "^7.4.5",
    "@babel/preset-env": "^7.4.5",
    "@babel/preset-react": "^7.0.0",
    "react": "^16.8.6",
    "react-dom": "^16.8.6"
  },
  "devDependencies": {
    "@babel/plugin-proposal-class-properties": "^7.4.4",
    "axios": "^0.19.0"
  }
}

.babelrc

{
    "presets": [
      "@babel/preset-env",
      "@babel/preset-react"
    ],
    "plugins": [
        [
          "@babel/plugin-proposal-class-properties",
          {
            "loose": true
          }
        ]
      ]
  }

Answer 1

你必须安装

npm install @babel/core @babel/plugin-proposal-class-properties @babel/preset-env @babel/preset-react babel-loader

和

更改输入和输出

---

const path = require('path')        
module.exports = {
  entry: path.resolve(__dirname,'src', 'app.js'),
  output: {
    path: path.resolve(__dirname, "public","dist",'javascript'),
    filename: 'bundle.js'
  },
  module: {
    rules: [
      {
        test: /\.(jsx|js)$/,
        exclude: /node_modules/,
        use: [{
          loader: 'babel-loader',
          options: {
            presets: [
              ['@babel/preset-env', {
                "targets": "defaults"
              }],
              '@babel/preset-react'
            ],
            plugins: [
              "@babel/plugin-proposal-class-properties"
            ]
          }
        }]
      }
    ]
  }
}

Answer 2

我正在使用plugin-proposal-class-propterties，它可以工作，这是我的 JSON 配置文件.babelrc

{
  "presets": ["@babel/preset-env"],
  "plugins": [
    [
      "@babel/plugin-proposal-class-properties",
      {"loose": true}
    ]
  ]
}

Answer 3

尝试创建一个文件babel.config.js 并使用module.exports 导出配置。我也相信您不需要loose 选项：

babel.config.js:

module.exports = {
  presets: ["@babel/preset-env", "@babel/preset-react"],
  plugins: ["@babel/plugin-proposal-class-propterties"]
};