webpack config file

webpack.config.js

module.exports = {
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        exclude: /node_modules/,
        use: {
          loader: "babel-loader",
          options: {
            "presets": ["@babel/preset-env", "@babel/preset-react"],
            "plugins": ['@babel/plugin-proposal-class-properties']
          }
        }
      }
    ]
  }
}