conditional-babel-core.js

function conditionalRequireModuleByPath(modulePath, condition) {
  try {
    var packageJson = require(path.join(modulePath, './package.json'))
    if (condition(packageJson)) {
      return require(path.join(
        modulePath,
        './',
        packageJson.main || 'index.js'
      ))
    }
  } catch (err) {}
  return null
}

function loadBabelCoreVersions() {
  var pathBabelCoreRoot = path.join(__dirname, '../node_modules/babel-core')
  var pathBabelCore6 = path.join(
    __dirname,
    '../node_modules/babelcore6/node_modules/babel-core/'
  )
  var pathBabelCore7 = path.join(
    __dirname,
    '../node_modules/babelcore7/node_modules/babel-core/'
  )

  var checkVersion6 = function(info) {
    return info.version.indexOf('6') === 0
  }

  var checkVersion7 = function(info) {
    return info.version.indexOf('7') === 0
  }

  var babel6 =
    conditionalRequireModuleByPath(pathBabelCoreRoot, checkVersion6) ||
    conditionalRequireModuleByPath(pathBabelCore6, checkVersion6)

  var babel7 =
    conditionalRequireModuleByPath(pathBabelCoreRoot, checkVersion7) ||
    conditionalRequireModuleByPath(pathBabelCore7, checkVersion7)

  return {
    babel6: babel6,
    babel7: babel7
  }
}