react on rails rendering server using Node.js

server.js

// client/node/server.js
// https://github.com/shakacode/react_on_rails/blob/master/docs/additional-reading/node-server-rendering.md
var net = require('net');
var fs = require('fs');

var bundlePath = '../../app/assets/webpack/';
var bundleFileName = 'webpack-bundle.js';

var currentArg;

function Handler() {
  this.queue = [];
  this.initialized = false;
}

Handler.prototype.handle = function (connection) {
  var callback = function () {
    connection.setEncoding('utf8');
    connection.on('data', (data)=> {
      console.log('Processing request: ' + data);
      var result = eval(data);
      connection.write(result);
    });
  };

  if (this.initialized) {
    callback();
  } else {
    this.queue.push(callback);
  }
};

Handler.prototype.initialize = function () {
  console.log('Processing ' + this.queue.length + ' pending requests');
  var callback;
  while (callback = this.queue.pop()) {
    callback();
  }

  this.initialized = true;
};

var handler = new Handler();

process.argv.forEach((val) => {
  if (val[0] == '-') {
    currentArg = val.slice(1);
    return;
  }

  if (currentArg == 's') {
    bundleFileName = val;
  }
});

try {
  fs.mkdirSync(bundlePath);
} catch (e) {
  if (e.code != 'EEXIST') throw e;
}

fs.watchFile(bundlePath + bundleFileName, (curr) => {
  if (curr && curr.blocks && curr.blocks > 0) {
    if (handler.initialized) {
      console.log('Reloading server bundle must be implemented by restarting the node process!');
      return;
    }

    require(bundlePath + bundleFileName);
    console.log('Loaded server bundle: ' + bundlePath + bundleFileName);
    handler.initialize();
  }
});

var unixServer = net.createServer(function (connection) {
  handler.handle(connection);
});

unixServer.listen('node.sock');

process.on('SIGINT', () => {
  unixServer.close();
  process.exit();
});