Reverse proxy server for serving bundled assets

reverse-proxy.js

var httpProxy = require('http-proxy'),
    fs = require('fs'),
    http = require('http'),
    url = require('url'),
    path = require('path'),
    iconv = require('iconv-lite');

var proxy = httpProxy.createProxyServer({});

proxy.on('error', function(e) {
  console.log(e);
});

var mime = {
    html: 'text/html',
    txt: 'text/plain',
    css: 'text/css',
    gif: 'image/gif',
    jpg: 'image/jpeg',
    png: 'image/png',
    svg: 'image/svg+xml',
    js: 'application/javascript',
    // ttf: 'font/ttf',
    ttf: 'application/octet-stream',
    woff: 'application/font-woff',
    woff2: 'application/font-woff2'
};

http.createServer(function (req, res) {
  if (/\/api\/|\/app\/auth\//.exec(req.url)) {
    console.log(`proxying request ${req.url}`)
    proxy.web(req, res, { target: 'http://benchprep.localhost' });
  }
  else {
    let file;
    if (/\/app\//.exec(req.url)) {
      console.log(`requesting local file ${req.url}`)
      file = url.parse(req.url).pathname;
    } else {
      console.log(`requesting index ${req.url}`)
      file = '/index.html'
    }

    var type = mime[path.extname(file).slice(1)] || 'text/plain';
    console.log(`reading path ${__dirname + file} of mime type ${type}`);
    var s = fs.createReadStream(__dirname + file);
    s.on('open', function () {
        var stats = fs.statSync(__dirname + file)
        var fileSizeInBytes = stats["size"]
        res.setHeader('Content-Type', type);
        res.setHeader('Vary', 'Accept-Encoding');
        if (/\/app\/assets\/benchprep-assets\/fonts\//.exec(req.url)) {
          s
            .pipe(iconv.decodeStream('utf-8'))
            .pipe(iconv.encodeStream('utf-16'))
            .pipe(res);
        }   
        else {
          s.pipe(res);
        }
    });
    s.on('error', function () {
        res.setHeader('Content-Type', 'text/plain');
        res.statusCode = 404;
        res.end('Not found');
    });
  }
}).listen(8080);