解决Vue-cli3没有vue.config.js文件夹及配置vue项目域名的问题

module.exports = {
 // 基本路径 baseURL已经过时
 publicPath: './', 
 // 输出文件目录
 outputDir: 'dist',
 // eslint-loader 是否在保存的时候检查
 lintOnSave: true,
 // use the full build with in-browser compiler?
 // https://vuejs.org/v2/guide/installation.html#Runtime-Compiler-vs-Runtime-only
 // compiler: false,
 // webpack配置
 // see https://github.com/vuejs/vue-cli/blob/dev/docs/webpack.md
 chainWebpack: () => {},
 configureWebpack: () => {},
 // vue-loader 配置项
 // https://vue-loader.vuejs.org/en/options.html
 // vueLoader: {},
 // 生产环境是否生成 sourceMap 文件
 productionSourceMap: true,
 // css相关配置
 css: {
  // 是否使用css分离插件 ExtractTextPlugin
  extract: true,
  // 开启 CSS source maps?
  sourceMap: false,
  // css预设器配置项
  loaderOptions: {},
  // 启用 CSS modules for all css / pre-processor files.
  modules: false
 },
 // use thread-loader for babel & TS in production build
 // enabled by default if the machine has more than 1 cores
 parallel: require('os').cpus().length > 1,
 // 是否启用dll
 // See https://github.com/vuejs/vue-cli/blob/dev/docs/cli-service.md#dll-mode
 // dll: false,
 // PWA 插件相关配置
 // see https://github.com/vuejs/vue-cli/tree/dev/packages/%40vue/cli-plugin-pwa
 pwa: {},
 // webpack-dev-server 相关配置
 devServer: {
  open: process.platform === 'darwin',
  disableHostCheck: true,
  host: 'www.test.com',//如果是真机测试，就使用这个IP
  port: 1234,
  https: false,
  hotOnly: false,
  before: app => {}
 },
 // 第三方插件配置
 pluginOptions: {
  // ...
 }
 }

 host: 'www.test.com',//自定义域名
 port: 1234,//自定义端口