This is Node notes

http模块

const http = require('http'); // 引入http模块
http.createServer(function(req,res) { //创建服务
    res.end("hello world"); //服务端输出       
}).listen(80);

express模块

const express = require('express');
const app = express();
app.all("*", function(req, res, next) { //跨域
   if (!req.get("Origin")) return next();
   // use "*" here to accept any origin
   res.set("Access-Control-Allow-Origin", "*");
   // res.set("Access-Control-Allow-Headers", "X-Requested-With, Content-Type");
   res.set("Access-Control-Allow-Methods", "GET,POST");
   // res.set('Access-Control-Allow-Max-Age', 3600);
   if ("OPTIONS" === req.method) return res.send(200);
   next();
});

mongoose模块

const mongoose=require('mongoose'); // 引入模块
const url = `mongodb://127.0.0.1:27017/runoob`; // 数据库地址
mongoose.connect(url,{  // 连接数据库
    useNewUrlParser: true,
    useCreateIndex: true
});
mongoose.connection.on('connected',() =>{ // 数据库成功回调
    console.log('数据库连接成功');
})

fs模块

const fs = require("fs");
fs.readFile('input.txt', function (err, data) {
   if (err) {
       return console.error(err);
   }
   console.log("异步读取: " + data.toString());
});