babel.config.js

module.exports = {
  presets: [require.resolve('@docusaurus/core/lib/babel/preset')],
  plugins: [
    ["@babel/plugin-proposal-class-properties"],
    ["@babel/plugin-proposal-private-property-in-object", { "loose": false }],
    ["@babel/plugin-proposal-private-methods", { "loose": false }]
  ]
};