2020 全站之路-Node.js 系列

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! 
powered by koa.js";
});

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