dynamic-path-to-static-assets-in-express.js

/*

  Create a folder called `folder-of-code` and then inside of that folder put
  other folders like foo and bar with different assets in them. Then run this
  server and notice how the static directory served will change depending on
  wether you hit `http://foo.lvh.me` and `http://bar.lvh.me`.

  Note you could rework this example to change the folder context depending on
  something in `req.params.*` but for this example we are using the wildcard
  subdomain afforded to us by the *.lvh.me domain which resolves
  to 127.0.0.1.
  
  Thanks to `https://github.com/chrisekelley` for laying the groundwork of this 
  example in `https://github.com/tangerine-community/tangerine/tree/v3`.
  
*/

const express = require('express');
const path = require('path')

// Set up app.
var app = express();

// Intercept all routes.
app.all('*', function (req, res) {
  const folderOfCodeToLookInDeterminedBySubdomain = req.headers.host.split('.')[0]
  return express.static(path.join(__dirname, 'folders-of-code', folderOfCodeToLookInDeterminedBySubdomain)).apply(this, arguments);
});

// Listen to on port 80.
app.listen(80, function () {
  console.log('Proxy is listening on port 80');
});