transformer.js

const babel = require("babel-core");

/**
 * This is your `.babelrc` equivalent.
 */
const babelRC = {
  presets: [require("babel-preset-react-native")],
  plugins: [
    // The following plugin will rewrite imports. Reimplementations of node
    // libraries such as `assert`, `buffer`, etc. will be picked up
    // automatically by the React Native packager.  All other built-in node
    // libraries get rewritten to their browserify counterpart.
    [
      require("babel-plugin-rewrite-require"),
      {
        aliases: {
          constants: "constants-browserify",
          crypto: "crypto-browserify",
          dns: "node-libs-browser/mock/dns",
          domain: "domain-browser",
          fs: "react-native-level-fs",
          http: "stream-http",
          https: "https-browserify",
          net: "node-libs-browser/mock/net",
          os: "os-browserify/browser",
          path: "path-browserify",
          querystring: "querystring-es3",
          stream: "stream-browserify",
          _stream_duplex: "readable-stream/duplex",
          _stream_passthrough: "readable-stream/passthrough",
          _stream_readable: "readable-stream/readable",
          _stream_transform: "readable-stream/transform",
          _stream_writable: "readable-stream/writable",
          sys: "util",
          timers: "timers-browserify",
          tls: "node-libs-browser/mock/tls",
          tty: "tty-browserify",
          vm: "vm-browserify",
          zlib: "browserify-zlib",
          pbkdf2: "pbkdf2/browser",
          "websocket-stream": "websocket-stream/stream",
          cuid: "uuid"
        },
        throwForNonStringLiteral: true
      }
    ]
  ],
  sourceMaps: true
};

module.exports.transform = function transform(src, filename, options) {
  const babelConfig = Object.assign({}, babelRC, {
    filename,
    sourceFileName: filename
  });
  const result = babel.transform(src, babelConfig);
  return {
    ast: result.ast,
    code: result.code,
    map: result.map,
    filename: filename
  };
};