index.js

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 */
'use strict';

var path = require('path');

const plugins = [
    // class { handleClick = () => { } }
    require.resolve('babel-plugin-transform-class-properties'),
    // { ...todo, completed: true }
    require.resolve('babel-plugin-transform-object-rest-spread'),
    // function* () { yield 42; yield 43; }
    [require.resolve('babel-plugin-transform-regenerator'), {
      // Async functions are converted to generators by babel-preset-latest
      async: false
    }],
    // Polyfills the runtime needed for async/await and generators
    [require.resolve('babel-plugin-transform-runtime'), {
      helpers: false,
      polyfill: false,
      regenerator: true,
      // Resolve the Babel runtime relative to the config.
      moduleName: path.dirname(require.resolve('babel-runtime/package'))
    }],
    // The following two plugins are currently necessary to get
    // babel-preset-env to work with rest/spread. More info here:
    // https://github.com/babel/babel-preset-env#caveats
    // https://github.com/babel/babel/issues/4074
    // const { a, ...z } = obj;
    require.resolve('babel-plugin-transform-es2015-destructuring'),
    // const fn = ({ a, ...otherProps }) => otherProps;
    require.resolve('babel-plugin-transform-es2015-parameters')
  ];

// This is similar to how `env` works in Babel:
// https://babeljs.io/docs/usage/babelrc/#env-option
// We are not using `env` because it’s ignored in versions > babel-core@6.10.4:
// https://github.com/babel/babel/issues/4539
// https://github.com/facebookincubator/create-react-app/issues/720
// It’s also nice that we can enforce `NODE_ENV` being specified.
var env = process.env.BABEL_ENV || process.env.NODE_ENV;
if (env !== 'development' && env !== 'test' && env !== 'production') {
  throw new Error(
    'Using `babel-preset-react-app` requires that you specify `NODE_ENV` or '+
    '`BABEL_ENV` environment variables. Valid values are "development", ' +
    '"test", and "production". Instead, received: ' + JSON.stringify(env) + '.'
  );
}

if (env === 'development' || env === 'test') {
  plugins.push.apply(plugins, [
    // Adds component stack to warning messages
    require.resolve('babel-plugin-transform-react-jsx-source'),
    // Adds __self attribute to JSX which React will use for some warnings
    require.resolve('babel-plugin-transform-react-jsx-self')
  ]);
}

if (env === 'test') {
  module.exports = {
    presets: [
      // ES features necessary for user's Node version
      [require('babel-preset-env').default, {
        targets: {
          node: parseFloat(process.versions.node),
        },
      }],
      // JSX, Flow
      require.resolve('babel-preset-react')
    ],
    plugins: plugins
  };
} else {
  module.exports = {
    presets: [
      // Latest stable ECMAScript features
      require.resolve('babel-preset-latest'),
      // JSX, Flow
      require.resolve('babel-preset-react')
    ],
    plugins: plugins
  };

  if (env === 'production') {
    // Optimization: hoist JSX that never changes out of render()
    // Disabled because of issues:
    // * https://github.com/facebookincubator/create-react-app/issues/525
    // * https://phabricator.babeljs.io/search/query/pCNlnC2xzwzx/
    // * https://github.com/babel/babel/issues/4516
    // TODO: Enable again when these issues are resolved.
    // plugins.push.apply(plugins, [
    //   require.resolve('babel-plugin-transform-react-constant-elements')
    // ]);
  }
}