Start your first hello world application Koa

Initialization package.json

npm init

AnSo koa

npm install koa

Creating app.js

// 导入的是一个class，因此用大写的Koa表示:
const Koa = require('koa');

// 创建一个Koa对象表示web app本身:
const app = new Koa();

// 对于任何请求，app将调用该异步函数处理请求：
app.use(async (ctx, next) => {
    await next();
    // 设置response的Content-Type:
    ctx.response.type = 'text/html';
    // 设置response的内容:
    ctx.response.body = '<h1>Hello, world!</h1>';
});

// 在端口3005监听:
app.listen(3005);

Parameters ctxare passed by the koa encapsulates requestand responsevariables can be accessed through it requestand response. nextKoa is passed in the next asynchronous function to be processed.

The asyncfunction is called asynchronous marker function in an asynchronous function, you can awaitcall another asynchronous function.

start up

npm start

You can start your tour of koa