Allow set router host match

[yeliex]

const router = new Router({
    host: 'example.domain' // host === 'example.domain'
});

OR

const router = new Router({
    host: /.*\.example\.domain$/
});

Just for discussion currently, more test case would complete

[etroynov]

@yeliex in what cases it can be useful?

[titanism]

Closing, if you want to re-open a new PR with resolved conflicts and possibly add a few examples to README then ping us!

[titanism]

We have just published @koajs/router v11.0.0 which resolves this issue. This is mirrored to koa-router as well.

https://github.com/koajs/router/releases/tag/v11.0.0

This project is maintained by Forward Email and Lad.

[yeliex]

@titanism @etroynov sorry for the late response. (never image the repo would be re-active)

as PR describes, it is for a server with many hosts, and the same path in each host may different.

for example

const routerA = new Router({
    host: 'a.domain'
});

routerA.get('/', () => {}) // return page for http://a.domain

const routerB = new Router({
    host: 'b.domain'
});

routerB.get('/', () => {}) // return page for http://b.domain

if want to do this in current version, we should detect the host in controller function.

[titanism]

Thank you - just submit a new PR if you'd like! 🙇

[yeliex]

#156