# 一拳搞定 Node.js | 如何运行一个 node 项目本文介绍如何在本地启动 nodejs 项目。 ## 一、前言最近要搭建自动化运维平台，前后端的生杀大权都随自己定，前端的技术选型了蚂蚁的 `ant design pro`，于是乎把折腾过的 `node` 和 `react` 的相关知识记录下。注意： - 本文需要读者具备基础的编程能力以及对计算机网络的基本了解，一些常用术语限于篇幅不再展开。 - 本文基于 mac 系统开发，如果 win 下有不一致的情况请自行对照相关命令。 ## 二、准备环境 ### 2.1、安装 Node.js Node.js 发布版本分为 Current 和 LTS 两类，前者每 6 个月迭代一个大版本，快速提供新增功能和问题修复，后者以 30 个月为一个大周期，为生产环境提供稳定依赖。当前 Node.js 最新 LTS 版本为 12.18.2，本文以此版本作为运行环境，可以在官网下载并安装。安装完成后，在命令行输入 `node --version` 查看输出是否为 `v12.8.2`，如果一致，那么安装成功。另外，有兴趣的读者可以尝试通过 `nvm / nvm-windows` 管理多个 Node.js 版本，此处不是本文重点不再展开。我本机的版本： ```bash $ node -v v12.18.2 ``` ## 三、创建 node 项目 ### 3.1 初始化工程 #### 3.1.1 创建并进入项目目录 ```bash mkdir node-sample && cd node-sample ``` #### 3.1.2 初始化 package.json ```bash $ npm init This utility will walk you through creating a package.json file. It only covers the most common items, and tries to guess sensible defaults. See `npm help init` for definitive documentation on these fields and exactly what they do. Use `npm install ` afterwards to install a package and save it as a dependency in the package.json file. Press ^C at any time to quit. package name: (sample) demo version: (1.0.0) 0.1.0 description: demo node entry point: (index.js) test command: git repository: keywords: author: license: (ISC) About to write to /Users/tc/Documents/workspace_2020/node-sample/package.json: { "name": "demo", "version": "0.1.0", "description": "demo node", "main": "index.js", "scripts": { "test": "echo \"Error: no test specified\" && exit 1" }, "author": "", "license": "ISC" } Is this OK? (yes) yes ``` 查看生成的文件或目录 ```bash $ ls node_modules package-lock.json package.json ``` #### 3.1.3 使用 express 安装 [express](https://expressjs.com/) ```bash npm install express ``` 创建目录和文件 ```bash mkdir src touch src/server.js ``` 编写 `server.js` ```js const express = require('express') const app = express() const port = 3000 app.get('/', (req, res) => { res.send('Hello World!') }) app.listen(port, () => { console.log(`Example app listening at http://localhost:${port}`) }) ``` #### 3.1.4 启动服务启动 ```bash $ node src/server.js Example app listening at http://localhost:3000 ``` 请求 {{< figure src="/2020/10/nodejs-start/request.jpg" title="请求" >}} 停止服务 ```bash control + c ``` 端口是否在使用 ```bash $ lsof -i:3000 ``` ### 3.2、静态资源服务器 #### 3.2.1 创建目录和文件创建 public 文件夹 ```bash mkdir src ``` 创建 HTML 文件 ```bash touch src/index.html ``` 查看目录 ```bash $ tree -L 1 . ├── index.js ├── node_modules ├── package-lock.json ├── package.json ├── public └── src ``` #### 3.2.2 编写 index.html ```HTML

It works!

``` #### 3.2.3 编写 server.js ```js const express = require('express') const { resolve } = require('path'); const { promisify } = require('util'); const app = express() const port = parseInt(process.env.PORT || '3000'); const publicDir = resolve('public'); async function bootstrap() { app.use(express.static(publicDir)) await promisify(app.listen.bind(app, port))(); console.log(`> Started on port http://localhost:${port}`); } bootstrap(); ``` #### 3.2.4 启动服务启动 ```bash npm start > demo@0.1.0 start /Users/tc/Documents/workspace_2020/node-sample > node src/server.js > Started on port http://localhost:3000 ``` 请求 {{< figure src="/2020/10/nodejs-start/request2.jpg" title="请求" >}} ## 四、碰到问题 ### 4.1 端口被占用配置好 package.json 的 start script 后，启动项目。 ```bash npm start > demo@0.1.0 start /Users/tc/Documents/workspace_2020/node-sample > node src/server.js events.js:292 throw er; // Unhandled 'error' event ^ Error: listen EADDRINUSE: address already in use :::3000 at Server.setupListenHandle [as _listen2] (net.js:1313:16) at listenInCluster (net.js:1361:12) at Server.listen (net.js:1447:7) at Function.listen (/Users/tc/Documents/workspace_2020/node-sample/node_modules/express/lib/application.js:618:24) at internal/util.js:297:30 at new Promise () at bound listen (internal/util.js:296:12) at bootstrap (/Users/tc/Documents/workspace_2020/node-sample/src/server.js:15:46) at Object. (/Users/tc/Documents/workspace_2020/node-sample/src/server.js:19:1) at Module._compile (internal/modules/cjs/loader.js:1138:30) Emitted 'error' event on Server instance at: at emitErrorNT (net.js:1340:8) at processTicksAndRejections (internal/process/task_queues.js:84:21) { code: 'EADDRINUSE', errno: 'EADDRINUSE', syscall: 'listen', address: '::', port: 3000 } npm ERR! code ELIFECYCLE npm ERR! errno 1 npm ERR! demo@0.1.0 start: `node src/server.js` npm ERR! Exit status 1 npm ERR! npm ERR! Failed at the demo@0.1.0 start script. npm ERR! This is probably not a problem with npm. There is likely additional logging output above. npm ERR! A complete log of this run can be found in: npm ERR! /Users/tc/.npm/_logs/2020-11-10T02_13_36_826Z-debug.log ``` 可以看到错误日志的日志文件位置和错误信息，地址已经被占用。 ## 五、参考 https://expressjs.com/en/starter/hello-world.html https://segmentfault.com/a/1190000023311123