前言

在我们开发的过程中，我们会使用webpack-dev-server实现自动刷新，webpack-dev-server会把编译后的文件全部保存在内存里，而不会写入到文件目录内。但当我们的开发是前端和后端在一个项目里的时候就不行了。我们可以使用webpack结合express实现自动编译刷新

配置webpack

首先就是配置webpack的配置。新建一个webpack.config.js文件

const path = require('path')
const webpack = require('webpack')
var hotMiddlewareScript = 'webpack-hot-middleware/client'

module.exports = {
 entry: {
 main: ['./src/main.js', hotMiddlewareScript]
 },
 mode: 'development',
 output: {
 path: path.resolve(__dirname, 'public'),
 filename: 'js/[name].js',
 publicPath: '/'
 },
 resolve: {
 extensions: ['.js']
 },
 plugins: [
 new webpack.optimize.OccurrenceOrderPlugin(),
 new webpack.HotModuleReplacementPlugin(),
 new webpack.NoEmitOnErrorsPlugin()
 ]
}

我们这里需要关注的是，每个entry后都要增加一个hotMiddlewareScript，还有就是增加3个插件
首先新建一个webpack.middleware文件，这里我们需要用到webpack-dev-middleware和 webpack-hot-middleware两个中间件。

const webpack = require('webpack')
const webpackDevMiddleware = require('webpack-dev-middleware')
const webpackHotMiddleware = require('webpack-hot-middleware')
const webpackConfig = require('./webpack.config')

module.exports = app => {
 let compiler = webpack(webpackConfig)

 app.use(webpackDevMiddleware(compiler, {
 publicPath: '/',
 stats: {
 colors: true,
 chunks: false
 }
 }))
 app.use(webpackHotMiddleware(compiler)) 
}

注意：webpack-dev-middleware和webpack-hot-middleware的静态资源服务仅仅用于开发环境。到了生产环境，应该使用express.static()。

下面编写express代码

const express = require('express')
const bodyParser = require('body-parser')
const {resolve} = require('path')
const webpackMiddleware=require('./webpack.middleware')

const router = express.Router()
const app=express()
const port = process.env.PORT || 3000

webpackMiddleware(app)

app.use(express.static(resolve(__dirname,'./public')))
app.use(bodyParser.json())
app.use(bodyParser.urlencoded({ extended: true }))

// ...代码

app.use(router)


app.listen(port, () => {
 console.log(`Server listening on http://localhost:${port}, Ctrl+C to stop`)
})

这样，我们在开发的时候，前端和后端都在同一个服务里运行了

总结