koa项目配置

热加载

nodemon 是一个工具，它通过在检测到目录中的文件更改时自动重新启动节点应用程序来帮助开发基于 Node.js 的应用程序。

安装

npm i nodemon -D

使用
在package.json中配置

 "scripts": {
    "dev": "nodemon ./src/index.js"
  },

npm run dev 启动

webpack配置

安装

webpcak常用包

npm i webpack webpack-cli -D
// 清理dist文件
npm i clean-webpack-plugin -D
// 对node_modules下的一些文件做排除处理
npm i webpack-node-externals -D
// babel相关
npm i @babel/core @babel/node @babel/preset-env babel-loader -D
// 设置环境变量
npm i cross-env -D
// 合并webpack配置
npm i webpack-merge -D
// 压缩打包的代码
npm install terser-webpack-plugin ---save-dev
// 清空dist
npm i  rimraf -D

webpack.config.js配置babel

const path = require('path')
// 排除不会使用到的模块
const nodeExcternals = require('webpack-node-externals')
const { CleanWebpackPlugin } = require('clean-webpack-plugin')
const webpackConfig = {
  target: 'node',
  mode: 'development',
  entry: {
    server: path.join(__dirname,'src/index.js')
  },
  output: {
    filename: '[name].bundle.js',
    path: path.join(__dirname, './dist'),
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        use: {
          loader: 'babel-loader',
        },
        exclude: [path.join(__dirname, '/node_modules')]
      }
    ]
  },
  devtool: 'eval-source-map',
  externals: [nodeExcternals()],
  plugins: [
    new CleanWebpackPlugin()
  ]
}
module.exports = webpackConfig**

webpack配置了babel后可以使用es6语法

运行

npx babel-node src/index.js

webpack调试

在Chrome中调试

调试命令

  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "dev": "nodemon ./src/index.js",
    "start": "nodemon --exec babel-node src/index.js",
    "webpack:debug": "node --inspect-brk ./node_modules/./webpack --inline --progress"
  },

运行

npm run webpack:debug

浏览器调试

在VScode中调试

添加nodemon配置并运行，在代码中打断点调试

优化webpack配置

检查项目中是否有依赖包更新

npm install -g npm-check-updates

// 查看ncu 指令
ncu --help

// 更新package.json
ncu -u

// 更新后删除node_modules 重新安装
rm -rf node_modules/

webpack整合

项目目录新建config文件夹
config目录新建utils.js，配置路径

const path = require('path')

exports.resolve = function resolve(dir) {
  return path.join(__dirname, '..', dir)
}
exports.APP_PATH = exports.resolve('src')
exports.DIST_PATH = exports.resolve('dist')

webpack.config.base.js

const path = require('path')
// 排除不会使用到的模块
const nodeExcternals = require('webpack-node-externals')
const { CleanWebpackPlugin } = require('clean-webpack-plugin')
const webpack = require('webpack')
const utils = require('./utils')
const webpackConfig = {
  target: 'node',
  entry: {
    server: path.join(utils.APP_PATH,'index.js')
  },
  output: {
    filename: '[name].bundle.js',
    path: utils.DIST_PATH,
  },
  module: {
    rules: [
      {
        test: /\.(js|jsx)$/,
        use: {
          loader: 'babel-loader',
        },
        exclude: [path.join(__dirname, '/node_modules')]
      }
    ]
  },

  externals: [nodeExcternals()],
  plugins: [
    new CleanWebpackPlugin(),
    new webpack.DefinePlugin({
      'process.env': {
        NODE_ENV: (process.env.NODE_ENV === 'production' || process.env.NODE_ENV === 'prod') ? "'production'" : "'development'"
      }
    })
  ]
}
console.log('webpackConfig', webpackConfig)
module.exports = webpackConfig

开发环境配置： webpack.config.dev.js

const webpackMerge = require('webpack-merge')

const baseWebpackConfig = require('./webpack.config.base')

const webpackConfig = webpackMerge(baseWebpackConfig, {
  devtool: 'eval-source-map', 
  mode: 'development' ,
  // webpack输入消息日志不需要传递出来
  status: { children: false }
})
module.exports = webpackConfig

生产环境配置：webpack.config.prod.js

const webpackMerge = require('webpack-merge')
const baseWebpackConfig = require('./webpack.config.base')

const TerserWebpackPlugin = require('terser-webpack-plugin')

const webpackConfig = webpackMerge.merge(baseWebpackConfig, {
  mode: 'production',
  // status: { children: false },
  optimization: {
    // webpack5 在不设置时（一般都不会设置），默认读取mode的值（默认是production或development）,DefinePlugin重新设置时与mode不一致，导致冲突
    nodeEnv: false,
    minimize: true,
    minimizer: [
      new TerserWebpackPlugin({
        terserOptions: {
          ecma: undefined,
          parse: {},
          compress: {
            warnings: false,
            // 是否注释console
            drop_console: false,
            dead_code: true,
            drop_debugger: true
          },
          mangle: true, // Note `mangle.properties` is `false` by default.
          module: false,
          // Deprecated
          output: {
            comments: false,
            beautify: false
          },
          format: null,
          toplevel: false,
          nameCache: null,
          ie8: false,
          keep_classnames: undefined,
          keep_fnames: false,
          safari10: false,
        },
      }),
    ],
    splitChunks: {
      cacheGroups: {
        commons: {
          name: 'commons',
          chunks: 'initial',
          minChunks: 3,
          enforce: true
        },
      },
    },
  },
})
module.exports = webpackConfig

package.js scripts新增

{
  "name": "koa_web",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1",
    "nodemon": "nodemon ./src/index.js",
    "start": "nodemon --exec babel-node src/index.js",
    "webpack:debug": "node --inspect-brk ./node_modules/./webpack --inline --progress",
    "build": "cross-env NODE_ENV=production webpack --config config/webpack.config.prod.js",
    "dev": "cross-env NODE_ENV=dev nodemon --exec babel-node --inspect ./src/index.js",
    "clean": "rimraf dist"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "@koa/cors": "^3.3.0",
    "koa": "^2.13.4",
    "koa-body": "^5.0.0",
    "koa-combine-routers": "^4.0.2",
    "koa-compose": "^4.1.0",
    "koa-compress": "^5.1.0",
    "koa-helmet": "^6.1.0",
    "koa-json": "^2.0.2",
    "koa-router": "^12.0.0",
    "koa-static": "^5.0.0"
  },
  "devDependencies": {
    "@babel/core": "^7.18.10",
    "@babel/node": "^7.18.10",
    "@babel/preset-env": "^7.18.10",
    "babel-loader": "^8.2.5",
    "clean-webpack-plugin": "^4.0.0",
    "cross-env": "^7.0.3",
    "nodemon": "^2.0.19",
    "rimraf": "^3.0.2",
    "terser-webpack-plugin": "^5.3.4",
    "webpack": "^5.74.0",
    "webpack-cli": "^4.10.0",
    "webpack-merge": "^5.8.0",
    "webpack-node-externals": "^3.0.0"
  }
}

完整koa demo

api/demoController.js

class DemoController {
  constructor () {}
  async demo(ctx) {
    ctx.body = {
      msg: 'body message'
    }
  }
}
export default new DemoController()

routers/demoRouter.js

import Router from "koa-router"
import demoController from "../api/demoController"
const router = new Router()

router.get('/demo', demoController.demo)

export default router

routers/routes.js

const combineRouters = require('koa-combine-routers')
import demoController from './demoRouter'

export default combineRouters(demoController)

src/index.js

import koa from 'koa'
import router from './routers/routes'
import cors from '@koa/cors'
import koabody from 'koa-body'
import json from 'koa-json'
import path from 'path'
import koaHelmet from 'koa-helmet'
import statics from 'koa-static'
import compose from 'koa-compose'
import compress from 'koa-compress'

const app = new koa()

// 是否为开发模式
const isDevMode = process.env.NODE_ENV === 'production' ? false : true

// koa-compose 整合中间件
const middleware = compose([
  koabody(),
  statics(path.join(__dirname, '../public')),
  cors(),
  json({ pretty: false, param: 'pretty'}),
  koaHelmet()
])

// 如果是生产模式就压缩中间件
if (!isDevMode) {
  app.use(compress())
}

app.use(middleware)
app.use(router())

app.listen(3000)