relative-url

convert a partial url into an absolute url from your current location.

In the WebSocket api, it expects a fully qualified url, but this is awkward because we want to develop on localhost, and then deploy to a server with a proper domain, with a different port.

We want to create a WebSocket at a path, and get whatever domain we are on.

This module generalized wsurl

api: rurl(url, location, protocolMap, defaultProtocol)

url is your partial url, it will be described below. location should be your is window.location or the output of require('url').parse(absoluteUrl)

if you want to change the protocol, protocol map is a object mapping current to desired protocol.

for websockets, you'll probably want: {http: 'ws', https: 'wss'}

defaultProtocol is what to set the protocol to otherwise. for example, 'ws' if defaultProtocol is not provided the output protocol will the the same as location.protocol

examples

for the following location:

var location = {
  protocol: 'http',
  host: 'server.com',
  pathname '/foo'
} //OR get this from window.location

var protocolMap = {http: 'ws', https: 'wss'}

var defaultProtocol : 'ws'

var rurl = require('relative-url')
function relative (url) {
  return rurl(url, location, protocolMap, defaultProtocol) 
}

and the above mentioned settings (suitable for websockets) output will be as following.

relative('/')            // => ws://server.com/
relative('/bar')         // => ws://server.com/bar
relative('//client.com') // => ws://client.com/
relative('//:9999')      // => ws://server.com:9999/
relative('?q=search'     // => ws://server.com/foo?q=search

note that // denotes the start of the host. if you want to set the port without changing the domain, you must still use // otherwise the url module will think it's a path. I considered detecting that, but then i saw this comment and got scared of learning too much about urls.

License

MIT