116 lines
3.9 KiB
Markdown
116 lines
3.9 KiB
Markdown
<img src="https://dl.dropboxusercontent.com/u/6396913/koa/logo.png" alt="koa middleware framework for nodejs" width="255px" />
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[![gitter][gitter-image]][gitter-url]
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[![NPM version][npm-image]][npm-url]
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[![build status][travis-image]][travis-url]
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[![Test coverage][coveralls-image]][coveralls-url]
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Expressive HTTP middleware 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. Koa's use of generators also greatly increases the readability and robustness of your application.
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Only methods that are common to nearly all HTTP servers are integrated directly into Koa's small ~550 SLOC codebase. This
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includes things like content negotiation, normalization of node inconsistencies, redirection, and a few others.
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Koa is not bundled with any middleware.
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## Installation
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```
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$ npm install koa
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```
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Koa is supported in node v4+ and node v0.12 with the `--harmony-generators` or `--harmony` flag.
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## v2 Alpha
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Koa v2 is currently in alpha. In this new version, the middleware function signature completely changes in favor of ES2015-2016 syntax:
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```js
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// uses async arrow functions
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app.use(async (ctx, next) => {
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try {
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await next() // next is now a function
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} catch (err) {
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ctx.body = { message: err.message }
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ctx.status = err.status || 500
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}
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})
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app.use(async ctx => {
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const user = await User.getById(ctx.session.userid) // await instead of yield
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ctx.body = user // ctx instead of this
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})
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```
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To learn more about Koa v2, follow [this issue](https://github.com/koajs/koa/issues/533).
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To try Koa v2, `npm install koa@next`.
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## Community
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- [API](docs/api/index.md) documentation
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- [Badgeboard](https://koajs.github.io/badgeboard) and list of official modules
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- [Examples](https://github.com/koajs/examples)
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- [Middleware](https://github.com/koajs/koa/wiki) list
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- [Wiki](https://github.com/koajs/koa/wiki)
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- [G+ Community](https://plus.google.com/communities/101845768320796750641)
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- [Reddit Community](http://reddit.com/r/koajs)
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- [Mailing list](https://groups.google.com/forum/#!forum/koajs)
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- [Guide](docs/guide.md)
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- [FAQ](docs/faq.md)
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- [中文文档](https://github.com/turingou/koa-guide)
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- __[#koajs]__ on freenode
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## Getting started
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- [Kick-Off-Koa](https://github.com/koajs/kick-off-koa) - An intro to koa via a set of self-guided workshops.
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- [Workshop](https://github.com/koajs/workshop) - A workshop to learn the basics of koa, Express' spiritual successor.
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- [Introduction Screencast](http://knowthen.com/episode-3-koajs-quickstart-guide/) - An introduction to installing and getting started with Koa
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## Example
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```js
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var koa = require('koa');
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var app = koa();
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// logger
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app.use(function *(next){
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var start = new Date;
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yield next;
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var ms = new Date - start;
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console.log('%s %s - %s', this.method, this.url, ms);
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});
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// response
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app.use(function *(){
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this.body = 'Hello World';
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});
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app.listen(3000);
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```
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## Running tests
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```
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$ make test
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```
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## Authors
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- [TJ Holowaychuk](https://github.com/tj)
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- [Jonathan Ong](https://github.com/jonathanong)
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- [Julian Gruber](https://github.com/juliangruber)
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- [Yiyu He](https://github.com/dead-horse)
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# License
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MIT
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[npm-image]: https://img.shields.io/npm/v/koa.svg?style=flat-square
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[npm-url]: https://npmjs.org/package/koa
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[travis-image]: https://img.shields.io/travis/koajs/koa/master.svg?style=flat-square
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[travis-url]: https://travis-ci.org/koajs/koa
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[coveralls-image]: https://img.shields.io/coveralls/koajs/koa/master.svg?style=flat-square
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[coveralls-url]: https://coveralls.io/r/koajs/koa?branch=master
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[gitter-image]: https://badges.gitter.im/Join%20Chat.svg
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[gitter-url]: https://gitter.im/koajs/koa?utm_source=badge&utm_medium=badge&utm_campaign=pr-badge&utm_content=badge
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[#koajs]: https://webchat.freenode.net/?channels=#koajs
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