.babelrc

// This file is formatted as JSON5 https://github.com/json5/json5
{
  presets: [
    // Transforms JSX
    '@babel/preset-react',
    // Transforms ES6 code and import/export statements
    [
      '@babel/preset-env',
      {
        targets: {
          electron: '2.0.0',
          node: '8',
          browsers: ['last 2 versions', 'not ie < 11']
        },
        // Only use polyfills necessary for target env
        useBuiltIns: 'usage',
        corejs: 3,
        shippedProposals: true
      }
    ]
  ],
  plugins: [
    // Reduces bundle size by sharing babel helpers between files
    ['@babel/plugin-transform-runtime', { corejs: 3 }],
    // Allows simpler defineMessages with react-intl
    // https://github.com/akameco/babel-plugin-react-intl-auto
    ['react-intl-auto', { filebase: true, removePrefix: 'src' }],
    // Turns flow type annotations into React.PropTypes for runtime
    // type checking. Deadcode wraps in NODE_ENV checks
    // ['flow-react-proptypes', { deadCode: true }],
    // Converts flow annotations into comment syntax
    // https://flow.org/en/docs/types/comments/
    '@babel/plugin-transform-flow-comments',
    // Allows directly declaring props and methods on a class instead of
    // binding them to `this` in the constructor
    '@babel/plugin-proposal-class-properties',
    // Allows short hand of Object.assign({}, a) as {...a}
    // useBuiltIns should be fine for our use-case, but could cause un-expected
    // results if trying to spread objects with a prototype chains. See
    // https://exploringjs.com/es6/ch_oop-besides-classes.html#sec_assigning-vs-defining-properties
    [
      '@babel/plugin-proposal-object-rest-spread',
      { loose: true, useBuiltIns: true }
    ]
  ],
  env: {
    esm: {
      plugins: [
        [
          'react-intl-auto',
          { filebase: true, extractComments: false, removePrefix: 'src' }
        ],
        // Creates shorter message hashes to reduce bundle size
        'react-intl-id-hash'
      ],
      presets: [
        [
          '@babel/preset-env',
          {
            targets: {
              // Our main target for these modules is the mapeo-desktop electron
              // application.
              electron: '2.0.0'
            },
            modules: false,
            // Only use polyfills necessary for target env
            useBuiltIns: 'usage',
            corejs: 3,
            shippedProposals: true
          }
        ]
      ]
    },
    cjs: {
      plugins: [
        [
          'react-intl-auto',
          { filebase: true, extractComments: false, removePrefix: 'src' }
        ],
        // Creates shorter message hashes to reduce bundle size
        'react-intl-id-hash'
      ]
    }
  }
}