Koa application is an object that contains a set of middleware functions, it is organized in a similar stack and execution, ** a key design point is to provide advanced "syntactic sugar" in its lower middleware layer. This improves interoperability, robustness, and more enjoyable writing middleware. ** This includes content such as negotiation, cache cleaning common tasks, proxy support and redirection methods
Essentials: Installation Node (edition> 7.6)
First, create a project:
npm init -y //初始化生产package.json 文件
npm install --save koa //安装koa包
Second, the compulsory hello world application:
New index.js file in the folder with the directory
const Koa = require('koa')
const app = new Koa()
app.use( async ( ctx ) => {
ctx.body = 'hello world'
})
app.listen(3000) //监听
console.log('[demo] start-quick is starting at port 3000')
Run node index.js;
# App.listen (...) method simply syntactic sugar of the following methods:
const http = require('http');
const Koa = require('koa');
const app = new Koa();
http.createServer(app.callback()).listen(3000);
This means that the same application at the same time as HTTP and HTTPS or more address:
const http = require('http');
const https = require('https');
const Koa = require('koa');
const app = new Koa();
http.createServer(app.callback()).listen(3000);
https.createServer(app.callback()).listen(3001);
