overleaf/services/web/babel.config.cjs

module.exports = {
  compact: false,
  presets: [
    [
      '@babel/env',
      {
        useBuiltIns: 'usage',
        // This version must be aligned with the `core-js` version in `package.json`
        corejs: { version: '3.46' },
        exclude: [
          // Exclude Array.prototype.push polyfill, as it's not needed and affects performance in Chrome
          'es.array.push',
          // Exclude objectSpread polyfill, as it's not needed and affects performance
          '@babel/plugin-transform-object-rest-spread',
          // Exclude _defineProperty polyfill, as it causes a bug without the objectSpread polyfill
          '@babel/plugin-transform-computed-properties',
          // Use native async functions, for performance
          '@babel/plugin-transform-async-to-generator',
          // Use native generators, for performance
          '@babel/plugin-transform-regenerator',
          // Use native async generators, for performance
          '@babel/plugin-transform-async-generator-functions',
          // Use native for-of loops, for performance
          '@babel/plugin-transform-for-of',
        ],
      },
    ],
    ['@babel/react', { runtime: 'automatic' }],
    '@babel/typescript',
  ],
  plugins: ['macros'],
  overrides: [
    // treat .cjs files (e.g. libraries symlinked into node_modules) as commonjs
    { test: /\.cjs$/, sourceType: 'script' },
    {
      // Use [\\/] for cross-platform path separator compatibility
      test: /[\\/]libraries[\\/]overleaf-editor-core[\\/].*\.js$/,
      sourceType: 'script',
    },
  ],
}