## 1.配置开发环境 ~~~ npm config set registry https://registry.npm.taobao.org npm init -y npm i koa -g npm i koa --save ~~~ ## 2.启动app.js ~~~ const Koa = require("koa"); const app = new Koa(); //ctx表示上下文,包含了request和response等信息 app.use(async ctx=>{ ctx.body = "hello world"; }); app.listen(3000); ~~~ ~~~ node app.js ~~~