babel.config.js

const path = require('path');
const generateReleaseInfo = require('./packages/x-license/generateReleaseInfo');

function resolveAliasPath(relativeToBabelConf) {
  const resolvedPath = path.relative(process.cwd(), path.resolve(__dirname, relativeToBabelConf));
  return `./${resolvedPath.replace('\\', '/')}`;
}

const defaultAlias = {
  '@mui/x-data-grid': resolveAliasPath('./packages/x-data-grid/src'),
  '@mui/x-data-grid-generator': resolveAliasPath('./packages/x-data-grid-generator/src'),
  '@mui/x-data-grid-pro': resolveAliasPath('./packages/x-data-grid-pro/src'),
  '@mui/x-data-grid-premium': resolveAliasPath('./packages/x-data-grid-premium/src'),
  '@mui/x-license': resolveAliasPath('./packages/x-license/src'),
  '@mui/x-date-pickers': resolveAliasPath('./packages/x-date-pickers/src'),
  '@mui/x-date-pickers-pro': resolveAliasPath('./packages/x-date-pickers-pro/src'),
  '@mui/x-charts': resolveAliasPath('./packages/x-charts/src'),
  '@mui/x-tree-view': resolveAliasPath('./packages/x-tree-view/src'),
  '@mui/x-tree-view-pro': resolveAliasPath('./packages/x-tree-view-pro/src'),
  '@mui/material-nextjs': '@mui/monorepo/packages/mui-material-nextjs/src',
  '@mui-internal/api-docs-builder': resolveAliasPath(
    './node_modules/@mui/monorepo/packages/api-docs-builder',
  ),
  '@mui-internal/test-utils': resolveAliasPath(
    './node_modules/@mui/monorepo/packages/test-utils/src',
  ),
  docs: resolveAliasPath('./node_modules/@mui/monorepo/docs'),
  test: resolveAliasPath('./test'),
  packages: resolveAliasPath('./packages'),
};

const productionPlugins = [
  ['babel-plugin-react-remove-properties', { properties: ['data-mui-test'] }],
];

module.exports = function getBabelConfig(api) {
  const useESModules = api.env(['modern', 'stable', 'rollup']);

  const presets = [
    [
      '@babel/preset-env',
      {
        bugfixes: true,
        browserslistEnv: process.env.BABEL_ENV || process.env.NODE_ENV,
        debug: process.env.MUI_BUILD_VERBOSE === 'true',
        modules: useESModules ? false : 'commonjs',
        shippedProposals: api.env('modern'),
      },
    ],
    [
      '@babel/preset-react',
      {
        runtime: 'automatic',
      },
    ],
    '@babel/preset-typescript',
  ];

  const plugins = [
    'babel-plugin-optimize-clsx',
    // Need the following 3 transforms for all targets in .browserslistrc.
    // With our usage the transpiled loose mode is equivalent to spec mode.
    ['@babel/plugin-transform-class-properties', { loose: true }],
    ['@babel/plugin-transform-private-methods', { loose: true }],
    ['@babel/plugin-transform-private-property-in-object', { loose: true }],
    ['@babel/plugin-transform-object-rest-spread', { loose: true }],
    [
      '@babel/plugin-transform-runtime',
      {
        useESModules,
        // any package needs to declare 7.4.4 as a runtime dependency. default is ^7.0.0
        version: '^7.4.4',
      },
    ],
    [
      'babel-plugin-transform-react-remove-prop-types',
      {
        mode: 'unsafe-wrap',
        ignoreFilenames: ['DataGrid.tsx', 'DataGridPro.tsx'],
      },
    ],
  ];

  if (process.env.NODE_ENV === 'test') {
    plugins.push(['@babel/plugin-transform-export-namespace-from']);
    // We replace `date-fns` imports with an aliased `date-fns@v3` version installed as `date-fns-v3` for tests.
    // The plugin is patched to only run on `AdapterDateFnsV3.ts`.
    // TODO: remove when we upgrade to date-fns v3 by default.
    plugins.push([
      'babel-plugin-replace-imports',
      {
        test: /date-fns/i,
        replacer: 'date-fns-v3',
        ignoreFilenames: 'AdapterDateFns.ts',
      },
    ]);
  }

  if (process.env.NODE_ENV === 'production') {
    plugins.push(...productionPlugins);

    if (process.env.BABEL_ENV) {
      plugins.push([
        'search-and-replace',
        {
          rules: [
            {
              search: '__RELEASE_INFO__',
              replace: generateReleaseInfo(),
            },
          ],
        },
      ]);
    }
  }

  return {
    assumptions: {
      noDocumentAll: true,
      // TODO: Replace "loose" mode with these:
      // setPublicClassFields: true,
      // privateFieldsAsProperties: true,
      // objectRestNoSymbols: true,
      // setSpreadProperties: true,
    },
    presets,
    plugins,
    ignore: [
      // Fix a Windows issue.
      /@babel[\\|/]runtime/,
      // Fix const foo = /{{(.+?)}}/gs; crashing.
      /prettier/,
    ],
    env: {
      coverage: {
        plugins: [
          'babel-plugin-istanbul',
          [
            'babel-plugin-module-resolver',
            {
              root: ['./'],
              alias: defaultAlias,
            },
          ],
        ],
      },
      development: {
        plugins: [
          [
            'babel-plugin-module-resolver',
            {
              alias: defaultAlias,
              root: ['./'],
            },
          ],
        ],
      },
      test: {
        sourceMaps: 'both',
        plugins: [
          [
            'babel-plugin-module-resolver',
            {
              root: ['./'],
              alias: defaultAlias,
            },
          ],
        ],
      },
    },
  };
};