1.安装node.js 查看版本 node -v

2.安装cnpm 

安装命令 ：npm install -g cnpm --registry=https://registry.npm.taobao.org

查看命令 ：cnpm -v

3.新建一个express-run.js 固定写法

var express = require("express"); //导入express  （下载）
var app = express();
var bodyParser = require("body-parser"); //导入body-parser  （下载）
app.use(bodyParser.json());
app.use(bodyParser.urlencoded({
    extended: true
}));

// 跨域
var allowCrossDomain = function (req, res, next) {
    res.header(Access-Control-Allow-Origin, *); //自定义中间件，设置跨域需要的响应头。
    res.setHeader(Access-Control-Allow-Methods, GET, POST, OPTIONS, PUT, DELETE); //允许任何方法
    res.setHeader(Access-Control-Allow-Headers, X-Requested-With,content-type,X-Session-Token); //允许任何类型
    next();
};
app.use(allowCrossDomain);




dataInfo = [
    { name: "苹果", count: 0, price: 10.01, check: false, },
    { name: "桃子", count: 0, price: 22.11, check: false, },
    { name: "橘子", count: 0, price: 8.12, check: false, },
]
//http://127.0.0.1:3000/list/fruitsData
app.get(/list/fruitsData, (req, res) => {
    res.status(200),
        res.send({ code: 200, describe: "success", data: dataInfo })
})

//http://127.0.0.1:3000/user/login
app.post(/user/login, (req, res) => {
    var { username, password } = req.body
    if (username != "xq" || password != "xq123") {
        return res.send({ code: 404, describe: "用户名或密码不正确" })
    } else {
        return res.send({ code: 200, describe: "success", data: { username, password } })
    }
})



const port = process.env.PORT || 3000
const host = process.env.HOST || 127.0.0.1
app.listen(port, host, () => {
    console.log(`Server is running on http://127.0.0.1:3000`);
});

4.安装依赖 cnpm install -S express body-parser

5.安装package.json 安装命令  npm init -y

6.启动命令 node express-run.js (也可以在package.json)

  "scripts": {
    "start": "node express-run.js"  
  },

自定义启动命令 npm run start