好。我正在引导一个简单的应用程序。我正在使用flow.js。我使用的预设是babel-preset-2015，babel-preset-
react和babel-preset-
stage-0。我必须在.babelrc内和webpack.config内放入相同的预设，所有这些预设才能正常工作。例如，如果我从webpack.config中将其移动，则会收到错误消息“未定义反应”。如果删除.babelrc和babel-
register，则会出现错误，因为我使用import和Flow.js批注。为什么会这样呢？如果将预设放入webpack.config中，则应该可以删除.babelrc，反之亦然。这就是我的代码现在全部正常工作的样子（减去一些对该问题不重要的文件）。

start-dev.js

require('babel-register')
require('./src/server/index.js')

index.js

/* @flow */

import Express from 'express'
import path from 'path'
import conf from '../conf/'

const APP_PORT: number = conf.APP_PORT
const PORT = process.env.PORT || APP_PORT

const app: Express = new Express()

// Middleware
app.set('views', path.join(__dirname, 'views'))
app.set('view engine', 'ejs')
app.use(Express.static(path.join(__dirname, '../', 'client', 'dist')))

// Routes
app.get('*', function (req: Object, res: Object) {
  res.render('index')
})

app.listen(PORT, function () {
  console.log(`Express server is up on port ${PORT}`)
})

app.js

import React from 'react'
import ReactDOM from 'react-dom'

ReactDOM.render(
  <h1>First</h1>,
  document.getElementById('app')
)

package.json

{
  "scripts": {
    "start-dev": "set \"NODE_ENV=development\" && babel-node ./start-dev.js",
    "start": "set \"NODE_ENV=development\" && node ./start-dev.js",
    "flow": "./node_modules/.bin/flow check",
    "standard": "node_modules/.bin/standard --verbose | node_modules/.bin/snazzy"
  },
  "dependencies": {
    "ejs": "^2.5.6",
    "express": "^4.15.2",
    "react": "^15.4.2",
    "react-dom": "^15.4.2"
  },
  "devDependencies": {
    "babel-cli": "^6.24.0",
    "babel-core": "^6.24.0",
    "babel-eslint": "^7.2.1",
    "babel-loader": "^6.4.1",
    "babel-preset-es2015": "^6.24.0",
    "babel-preset-react": "^6.23.0",
    "babel-preset-stage-0": "^6.22.0",
    "babel-register": "^6.24.0",
    "eslint": "^3.18.0",
    "eslint-config-standard": "^7.1.0",
    "eslint-plugin-flowtype": "^2.30.4",
    "eslint-plugin-react": "^6.10.3",
    "flow-bin": "^0.42.0",
    "snazzy": "^6.0.0",
    "standard": "^9.0.2",
    "webpack": "^2.3.2"
  }
}

.babelrc

{
  "passPerPreset": true,
  "presets": [
    "es2015",
    "react",
    "stage-0"
  ]
}

webpack.config.babel.js

'use strict'

import path from 'path'
const publicPath = path.resolve(__dirname, './src/client')

module.exports = {
  devtool: '#source-maps',
  performance: {
    hints: false
  },
  context: publicPath,
  entry: {
    bundle: './app.js'
  },
  output: {
    path: path.join(publicPath, 'dist'),
    filename: '[name].js',
    publicPath: '/dist/'
  },
  resolve: {
    extensions: ['.js', '.jsx']
  },
  module: {
    rules: [
      {
        test: /\.jsx?$/,
        exclude: /node_modules/,
        loader: 'babel-loader',
        options: {
          presets: [
            'react',
            'es2015',
            'stage-0'
          ]
        }
      }
    ]
  }
}