详解vue-cli 2.0配置文件(小结)(2)

/* eslint-disable */

// 首先检查node和npm的版本
require('./check-versions')()

// 获取配置文件中默认的配置
var config = require('../config')
// 如果node无法判断当前是开发环境还是生产环境，则使用config.dev.env.NODE_ENV作为当前的环境
if (!process.env.NODE_ENV) {
 process.env.NODE_ENV = JSON.parse(config.dev.env.NODE_ENV)
}

var opn = require('opn')// 用来在起来服务之后，打开浏览器并跳转指定URL
var path = require('path')// node自带文件路径工具
var express = require('express')// node框架express（本地开发的核心，起服务）
var webpack = require('webpack')// webpack,压缩打包
var proxyMiddleware = require('http-proxy-middleware')// 中间件
var webpackConfig = require('./webpack.dev.conf')// 开发环境的webpack配置
var mockMiddleware = require('../config/dev.mock')// 开发环境本地mock数据中间件

var port = process.env.PORT || config.dev.port
var autoOpenBrowser = !!config.dev.autoOpenBrowser
var proxyTable = config.dev.proxyTable

var app = express()// 起服务
var compiler = webpack(webpackConfig)// webpack进行编译

// webpack-dev-middleware将编译的文件放在内存中，后续注入
var devMiddleware = require('webpack-dev-middleware')(compiler, {
 publicPath: webpackConfig.output.publicPath,
 quiet: true
})
// 热加载
var hotMiddleware = require('webpack-hot-middleware')(compiler, {
 log: false,
 heartbeat: 2000
})
compiler.plugin('compilation', function (compilation) {
 compilation.plugin('html-webpack-plugin-after-emit', function (data, cb) {
 hotMiddleware.publish({ action: 'reload' })
 cb()
 })
})

// proxy api requests
// proxyTable中的配置挂载到express中
Object.keys(proxyTable).forEach(function (context) {
 var options = proxyTable[context]
 if (typeof options === 'string') {
 options = { target: options }
 }
 app.use(proxyMiddleware(options.filter || context, options))
})

// 处理后退的时候匹配资源
app.use(require('connect-history-api-fallback')())

// 暂存在内存的webpack编译后的文件挂载到express上
app.use(devMiddleware)

// 将本地mock中间件挂载到express上
app.use(mockMiddleware);

// 热加载挂载到express上
app.use(hotMiddleware)

// 拼static静态资源文件路径
var staticPath = path.posix.join(config.dev.assetsPublicPath, config.dev.assetsSubDirectory)
// express为静态资源提供服务
app.use(staticPath, express.static('./static'))

var uri = 'http://localhost:' + port

var _resolve
var readyPromise = new Promise(resolve => {
 _resolve = resolve
})

console.log('> Starting dev server...')
devMiddleware.waitUntilValid(() => {
 console.log('> Listening at ' + uri + '\n')
 if (autoOpenBrowser && process.env.NODE_ENV !== 'testing') {
 opn(uri)
 }
 _resolve()
})
// 通过配置的端口，自动打开浏览器，并跳转拼好的URL，至此，发开环境已经跑起来了
var server = app.listen(port)

module.exports = {
 ready: readyPromise,
 close: () => {
 server.close()
 }
}