Koa

koa

제품 정보

즐겨찾기

태그

Koa

프로그래밍 언어

공개 채팅

지원 계획

현재 사용할 수 있는 OSS 플랜이 없습니다.

저장소의 제공자 또는 기여자인 경우 OSS 플랜 추가를 시작할 수 있습니다.

OSS 플랜 추가
여기에서 자세히 알아보세요

이 오픈소스에 대한 플랜을 찾고 있다면 저희에게 문의해 주세요.

전문 공급자와 연락하실 수 있도록 도와드리겠습니다.

제품 세부 정보

Expressive middleware for node.js using ES2017 async functions Koa middleware framework for nodejs

gitter NPM version build status Test coverage OpenCollective Backers OpenCollective Sponsors PR's Welcome

Expressive HTTP middleware framework for node.js to make web applications and APIs more enjoyable to write. Koa's middleware stack flows in a stack-like manner, allowing you to perform actions downstream then filter and manipulate the response upstream.

Only methods that are common to nearly all HTTP servers are integrated directly into Koa's small ~570 SLOC codebase. This includes things like content negotiation, normalization of node inconsistencies, redirection, and a few others.

Koa is not bundled with any middleware.

Installation

Koa requires node v18.0.0 or higher for ES2015 and async function support.

$ npm install koa

Hello Koa

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

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

app.listen(3000);

Getting started

  • Kick-Off-Koa - An intro to Koa via a set of self-guided workshops.
  • Guide - Go straight to the docs.

Middleware

Koa is a middleware framework that can take two different kinds of functions as middleware:

  • async function
  • common function

Here is an example of logger middleware with each of the different functions:

async functions (node v7.6+)

app.use(async (ctx, next) => {
  const start = Date.now();
  await next();
  const ms = Date.now() - start;
  console.log(`${ctx.method} ${ctx.url} - ${ms}ms`);
});

Common function

// Middleware normally takes two parameters (ctx, next), ctx is the context for one request,
// next is a function that is invoked to execute the downstream middleware. It returns a Promise with a then function for running code after completion.

app.use((ctx, next) => {
  const start = Date.now();
  return next().then(() => {
    const ms = Date.now() - start;
    console.log(`${ctx.method} ${ctx.url} - ${ms}ms`);
  });
});

Koa v1.x Middleware Signature

The middleware signature changed between v1.x and v2.x. The older signature is deprecated.

Old signature middleware support will be removed in v3

Please see the Migration Guide for more information on upgrading from v1.x and using v1.x middleware with v2.x.

Context, Request and Response

Each middleware receives a Koa Context object that encapsulates an incoming http message and the corresponding response to that message. ctx is often used as the parameter name for the context object.

app.use(async (ctx, next) => { await next(); });

Koa provides a Request object as the request property of the Context.
Koa's Request object provides helpful methods for working with http requests which delegate to an IncomingMessage from the node http module.

Here is an example of checking that a requesting client supports xml.

app.use(async (ctx, next) => {
  ctx.assert(ctx.request.accepts('xml'), 406);
  // equivalent to:
  // if (!ctx.request.accepts('xml')) ctx.throw(406);
  await next();
});

Koa provides a Response object as the response property of the Context.
Koa's Response object provides helpful methods for working with http responses which delegate to a ServerResponse .

Koa's pattern of delegating to Node's request and response objects rather than extending them provides a cleaner interface and reduces conflicts between different middleware and with Node itself as well as providing better support for stream handling. The IncomingMessage can still be directly accessed as the req property on the Context and ServerResponse can be directly accessed as the res property on the Context.

Here is an example using Koa's Response object to stream a file as the response body.

app.use(async (ctx, next) => {
  await next();
  ctx.response.type = 'xml';
  ctx.response.body = fs.createReadStream('really_large.xml');
});

The Context object also provides shortcuts for methods on its request and response. In the prior examples, ctx.type can be used instead of ctx.response.type and ctx.accepts can be used instead of ctx.request.accepts.

For more information on Request, Response and Context, see the Request API Reference, Response API Reference and Context API Reference.

Koa Application

The object created when executing new Koa() is known as the Koa application object.

The application object is Koa's interface with node's http server and handles the registration of middleware, dispatching to the middleware from http, default error handling, as well as configuration of the context, request and response objects.

Learn more about the application object in the Application API Reference.

Documentation

Troubleshooting

Check the Troubleshooting Guide or Debugging Koa in the general Koa guide.

Running tests

$ npm test

Reporting vulnerabilities

To report a security vulnerability, please do not open an issue, as this notifies attackers of the vulnerability. Instead, please email dead_horse, jonathanong, and niftylettuce to disclose.

Authors

See AUTHORS.

Community

Job Board

Looking for a career upgrade?

Backers

Support us with a monthly donation and help us continue our activities.

Sponsors

Become a sponsor and get your logo on our README on Github with a link to your site.

License

MIT

문의하기

  • 비즈니스 개발자를 위한 최신 정보를 원하십니까? 소스 코드 프로젝트에 대한 PieceX 커뮤니티의 요구사항을 알아보세요. PieceX의 최신 무료 커뮤니티 코드를 빠르게 알려드립니다.
PieceX Logo