使用 concurrently 并行地运行多个命令（同时跑前端和后端的服务）

我现在有一个项目是这样的，前端是用 React 写的，后端是用 Nodejs，目录结构如下：

1 .
2 ├── README.md
3 ├── backend
4 ├── node_modules
5 ├── package.json
6 ├── public
7 ├── src
8 └── yarn.lock

这个 package.json 的内容如下：

 1 {
 2   "name": "crudtest",
 3   "version": "0.1.0",
 4   "private": true,
 5   "dependencies": {
 6     "classnames": "^2.2.5",
 7     "concurrently": "^3.5.1",
 8     "react": "^16.2.0",
 9     "react-dom": "^16.2.0",
10     "react-redux": "^5.0.7",
11     "react-router-dom": "^4.2.2",
12     "react-scripts": "1.1.1",
13     "redux": "^3.7.2",
14     "redux-thunk": "^2.2.0"
15   },
16   "scripts": {
17     "start": "react-scripts start",
18     "build": "react-scripts build",
19     "test": "react-scripts test --env=jsdom",
20     "eject": "react-scripts eject",
21   },
22   "devDependencies": {
23     "redux-devtools-extension": "^2.13.2"
24   },
25   "proxy": "http://localhost:8080"
26 }

而后端项目是放在 backend 这个目录中，其目录结构如下：

1 backend
2 ├── etc
3 ├── node_modules
4 ├── package-lock.json
5 ├── package.json
6 └── server.js

它的 package.json 文件，内容如下：

 1 {
 2   "name": "backend",
 3   "version": "1.0.0",
 4   "description": "",
 5   "main": "server.js",
 6   "scripts": {
 7     "test": "echo "Error: no test specified" && exit 1",
 8     "start": "nodemon --exec babel-node -- ./server.js"
 9   },
10   "keywords": [],
11   "author": "",
12   "license": "ISC",
13   "dependencies": {
14     "body-parser": "^1.18.2",
15     "express": "^4.16.2",
16     "mongodb": "^3.0.4"
17   },
18   "devDependencies": {
19     "babel-cli": "^6.26.0",
20     "babel-preset-es2015": "^6.24.1",
21     "nodemon": "^1.17.1"
22   }
23 }

现在前端项目要运行起来简单，只要运行如下命令即可。

$ npm run start

就会跑 3000 端口。

那么要运行服务器的程序的话，可能要这样：

1 $ cd backend
2 $ npm run start

就会跑 8080 端口。

那么有没有一种方法同时运行两个服务呢？

就是用一条命令跑两个服务。

解决方法如下：

1、在项目根目录下，运行：

1 $ npm i concurrently --save
2 或
3 $ yarn add concurrently

然后更改 package.json 文件，如下：

 1 {
 2   "name": "crudtest",
 3   "version": "0.1.0",
 4   "private": true,
 5   "dependencies": {
 6     "classnames": "^2.2.5",
 7     "concurrently": "^3.5.1",
 8     "react": "^16.2.0",
 9     "react-dom": "^16.2.0",
10     "react-redux": "^5.0.7",
11     "react-router-dom": "^4.2.2",
12     "react-scripts": "1.1.1",
13     "redux": "^3.7.2",
14     "redux-thunk": "^2.2.0"
15   },
16   "scripts": {
17     "start": "react-scripts start",
18     "build": "react-scripts build",
19     "test": "react-scripts test --env=jsdom",
20     "eject": "react-scripts eject",
21     "server": "npm start --prefix backend",
22     "dev": "concurrently "npm run server" "npm run start""
23   },
24   "devDependencies": {
25     "redux-devtools-extension": "^2.13.2"
26   },
27   "proxy": "http://localhost:8080"
28 }

主要添加了下面这两行：

1 "server": "npm start --prefix backend",
2 "dev": "concurrently "npm run server" "npm run start""

有了 --prefix backend 就不用 cd backend 了，也就是说运行 npm run server 就会跑后端的服务，相当于：

1 $ cd backend
2 $ npm run start

最后运行 npm run dev 相当于同时运行下面两条命令：

1 $ npm run server
2 $ npm run start

界面如下：

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