proxy.js:

var httpProxy = require('http-proxy');
var options   = { router: 'table.json' };

httpProxy.createServer(options).listen(80);

////////////////////////////////////////////////////
table.json:

{
   "router":
   {
      "domain1.com": "127.0.0.1:8080",
      "domain2.com": "127.0.0.1:8001"
   }
}