中文
devexamples

Koa Compose Middleware Pipeline Order

Compose Koa middleware functions in explicit execution order, tracing the onion model pass-through with early termination and downstream control.

JavascriptResilience

Code

snippet
import Koa from 'koa';
import compose from 'koa-compose';

async function timing(ctx, next) {
  const started = Date.now();
  await next();
  ctx.set('x-response-time', String(Date.now() - started));
}

async function guard(ctx, next) {
  if (ctx.path === '/internal') {
    ctx.status = 403;
    return; // early termination: downstream never runs
  }
  await next();
}

async function body(ctx) {
  ctx.body = { ok: true };
}

const app = new Koa();
app.use(compose([timing, guard, body]));

const pipeline = compose([timing, guard, body]);
const ctx = app.createContext(null, null);
await pipeline(ctx, () => Promise.resolve());
console.log('composed response headers:', ctx.response.status);

Related Examples