Node.js & Koa.js All In One

Node.js & Koa.js All In One

Koa.js

https://github.com/koajs/koa

https://koajs.com/

$ nvm install 7
# node.js 7 +
$ nvm install 10

$ npm i koa
$ node ./koa-app.js

const Koa = require('koa');
const app = new Koa();

app.use(async ctx => {
    ctx.body = 'Hello World';
});

app.listen(3000);

demos

const Koa = require('koa');
const app = new Koa();

// logger
app.use(async (ctx, next) => {
    await next();
    const rt = ctx.response.get('X-Response-Time');
    console.log(`${ctx.method} ${ctx.url} - ${rt}`);
});

// x-response-time
app.use(async (ctx, next) => {
    const start = Date.now();
    await next();
    const ms = Date.now() - start;
    ctx.set('X-Response-Time', `${ms}ms`);
});

// response
app.use(async ctx => {
    ctx.body = 'Hello World';
});

app.listen(3000);

// var http = require("http");

// //create a server object:
// http
//   .createServer(function(req, res) {
//     res.write("Hello World!"); //write a response to the client
//     res.end(); //end the response
//   })
//   .listen(8080); //the server object listens on port 8080

const Koa = require("koa");
const app = new Koa();

const log = console.log;
// logger
app.use(async (ctx, next) => {
  await next();
  // middleware 1, 后执行
  const rt = ctx.response.get("X-Response-Time");
  log(`\nmiddleware 1, 后执行`, rt);
  log(`${ctx.method} ${ctx.url} - ${rt}`);
});

// x-response-time
app.use(async (ctx, next) => {
  const start = Date.now();
  await next();
  // middleware 2, 先执行
  const ms = Date.now() - start;
  log(`\nmiddleware 2, 先执行`, `${ms}ms`);
  ctx.set("X-Response-Time", `${ms}ms`);
});

// response
app.use(async (ctx, next) => {
  // log(`response ctx`, ctx);
  // await next();
  log(`\nmiddleware 0, 最后的 middleware 最先执行`);
  ctx.body = "Hello World! <br />powered by koa.js";
});

app.listen(3000);
// app.listen(8080);

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