koa的一些middleware

koa的一些常用的middleware

直接去github中的koa的wiki中搜

Frameworks

Frameworks, boilerplates and other starter kits using Koa.

Middleware

Known middleware for Koa, you may want to search npm with “koa” to find more.

Security

Body Parsing

Parameter Validation

Rate Limiting

Vhost

Routing and Mounting

Documentation

File Serving

koa-static

静态文件服务中间件,是koa-send的包装

安装

npm install koa-static

API

API
const Koa = require('koa');
const app = new Koa();
//有点不同哦，还是看下面例子好了
app.use(require('koa-static')(root, opts));

• root 根目录 String
• opts options object.

Options

• maxage 浏览cache的最大时间ms 默认 0
• hidden 允不允许改变隐藏文件. 默认 false
• index 默认文件名, 默认 ‘index.html’
• defer 如果为true, 在 return next()之后, 服务器允许任何一个downstream middleware 首先回应.
• gzip 当用户支持gzip格式, 并且.gz这种文件存在就行. 默认 true.
• br 同上 .br 格式存在时 (但要注意这个只用在https中). 默认 true.
• setHeaders Function to set custom headers on response.
• extensions 当在URL中没有匹配到扩展名时,那么会试着去从传过来的数组中匹配. 默认 false

Example

const serve = require('koa-static');
const Koa = require('koa');
const app = new Koa();

// $ GET /package.json
app.use(serve('.'));

// $ GET /hello.txt
app.use(serve('test/fixtures'));

// or use absolute paths
app.use(serve(__dirname + '/test/fixtures'));

app.listen(3000);

console.log('listening on port 3000');

SPDY

HTTP2

JSON and JSONP Responses

Compression

Caching

Authentication

Sessions

Templating

Services

CSS Preprocessor

Livereload

Error reporting

koa-onerror

就是一个抓错误的处理器 for koa, hack ctx.onerror.
就是handle all errors, steams’ and events’ errors

比koa-error使用简单,且抓的错误多

安装

npm install koa-onerror

使用

const fs = require('fs');
const koa = require('koa');
const onerror = require('koa-onerror');

const app = new koa();
//这里就是使用咯
onerror(app);

app.use(ctx => {
  // foo();
  ctx.body = fs.createReadStream('not exist');
});

Options

onerror(app, options);

• all: if options.all exist, ignore negotiation
• text: text error handler
• json: json error handler
• html: html error handler
• redirect: if accepct html, can redirect to another error page

check out default handler to write your own handler.

Status and Headers

koa-onerror will automatic set err.status as response status code, and err.headers as response headers.

Logging

koa-logger

Development style logger middleware for koa.

注意: koa-logger@2 支持 koa@2; 如果你想在 koa@1中使用, 请使用 koa-logger@1.

<-- GET /
--> GET / 200 835ms 746b
<-- GET /
--> GET / 200 960ms 1.9kb
<-- GET /users
--> GET /users 200 357ms 922b
<-- GET /users?page=2
--> GET /users?page=2 200 466ms 4.66kb

安装

npm install koa-logger

使用

const logger = require('koa-logger')
const Koa = require('koa')

const app = new Koa()
app.use(logger())

Notes

Recommended that you .use() this middleware near the top to “wrap” all subsequent middleware.
就是在顺序上放最上面来app.use(logger())

Metrics

Analytics

i18n or L10n

Response Transformation

Utilities

koa-convert

就是将只能在koa1中使用的middleware转换成koa2中能用的,当然也能反之咯.但注意有些不能转换 比如koa-router

安装

npm install koa-convert

使用

const Koa = require('koa') // koa v2.x
const convert = require('koa-convert')
const app = new Koa()
//这是正常是用koa2的middleware
app.use(modernMiddleware)
//这是使用koa2之前的版本,加上convert
app.use(convert(legacyMiddleware))
//这是一起用,混合
app.use(convert.compose(legacyMiddleware, modernMiddleware))

function * legacyMiddleware (next) {
  // before
  yield next
  // after
}

function modernMiddleware (ctx, next) {
  // before
  return next().then(() => {
    // after
  })
}

关于区分 legacy and modern middleware

就一个意思,通过 fn.constructor.name == 'GeneratorFunction'来判断版本.

API

就3个,实现不管新版本还是旧版本都能使用middleware
一个将老的middleware转成新的,
一个混合老的和新的middleware都转成新的,
一个将新的middleware转成老的

• convert()

modernMiddleware = convert(legacyMiddleware)

• convert.compose()

composedModernMiddleware = convert.compose(legacyMiddleware, modernMiddleware)
// or
composedModernMiddleware = convert.compose([legacyMiddleware, modernMiddleware])

• convert.back()

legacyMiddleware = convert.back(modernMiddleware)