@goa/cors


@goa/cors is Cross-Origin Resource Sharing (CORS) For Goa.

``sh
yarn add @goa/cors
`

Table Of Contents

- Table Of Contents
- API
- cors(config=: !CorsConfig): !Middleware
* CorsConfig
- Usage Events
- Copyright & License

API

The package is available by importing its default function:

`js
import cors from '@goa/cors'
`

cors(
  config=: !CorsConfig,
): !Middleware

__CorsConfig__: Options for the program.


There are 3 main use cases:

1. Accept any origin form the client

`js
import Goa from '@goa/koa'
import { aqt } from 'rqt'
import cors from '@goa/cors'

const goa = new Goa()
goa.use(cors())

goa.listen(async function() {
const { port } = this.address()
const url = http://localhost:${port}

// 1. accept origin from the host
const { headers } = await aqt(url, {
headers: {
origin: 'www.example.com',
},
})
console.log(headers)
this.close()
})
`
`js
{ vary: 'Origin',
'access-control-allow-origin': 'www.example.com',
'content-type': 'text/plain; charset=utf-8',
'content-length': '9',
date: 'Thu, 09 Jan 2020 14:43:05 GMT',
connection: 'close' }
`

2. Send out only specific origin

`js
import Goa from '@goa/koa'
import { aqt } from 'rqt'
import cors from '@goa/cors'

const goa = new Goa()
goa.use(cors({
origin: 'www.hello-world.com',
}))

goa.listen(async function() {
const { port } = this.address()
const url = http://localhost:${port}

// 2. only serve specific origin
const { headers } = await aqt(url, {
headers: {
origin: 'www.example.com',
},
})
console.log(headers)
this.close()
})
`
`js
{ vary: 'Origin',
'access-control-allow-origin': 'www.hello-world.com',
'content-type': 'text/plain; charset=utf-8',
'content-length': '9',
date: 'Thu, 09 Jan 2020 14:43:05 GMT',
connection: 'close' }
`

3. Pre-flight Requests Via OPTIONS (both above apply)

`js
import Goa from '@goa/koa'
import { aqt } from 'rqt'
import cors from '@goa/cors'

const goa = new Goa()
goa.use(cors({
origin: 'www.hello-world.com',
credentials: true,
maxAge: 1000,
allowMethods: ['POST', 'PUT'],
}))

goa.listen(async function() {
const { port } = this.address()
const url = http://localhost:${port}

// 3. respond to pre-flight request
const { statusCode, headers } = await aqt(url, {
method: 'OPTIONS',
headers: {
'Access-Control-Request-Method': 'POST',
origin: 'www.example.com',
},
})
console.log(statusCode, headers)
this.close()
})
`
`js
204 { vary: 'Origin',
'access-control-allow-origin': 'www.hello-world.com',
'access-control-allow-credentials': 'true',
'access-control-max-age': '1000',
'access-control-allow-methods': 'POST,PUT',
date: 'Thu, 09 Jan 2020 14:43:05 GMT',
connection: 'close' }
`

Usage Events

This middleware integrates with _Idio_ that collects middleware usage statistics to reward package maintainers. It will emit certain events to bill its usage:

1. headers: When setting the headers if origin was present.
1. options: When responding to pre-flight requests via the OPTIONS http method.

The usage is recorded via the ctx.neoluddite` context property set by a server such as _Idio_. In future, more fine-grained usage events might appear.

Copyright & License

GNU Affero General Public License v3.0

Affero GPL means that you're not allowed to use this middleware on the web unless you release the source code for your application. This is a restrictive license which has the purpose of defending Open Source work and its creators.

Please refer to the Idio license agreement for more info on dual-licensing. You're allowed to use this middleware without disclosing the source code if you sign up on neoluddite.dev package reward scheme.

Original Work by dead-horse & contributors licensed under MIT found in COPYING.

© Idio 2020