Simple Nodejs-Express reflection API

reflection-middleware.js

module.exports = function( app ){
  app.post('/__reflection', function( req, res, next ){
    const ip = req.headers[ 'x-forwarded-for' ] || req.connection.remoteAddress;
    console.log( 'IP', ip );
    if( ip !== '::ffff:127.0.0.1' ){
      return next();
    }
    let fn;
    try {
      eval( 'fn = ' + req.body.code );
    } catch (e) {
      e.status = 500;
      return next(e);
    }
    Promise.resolve()
      .then(fn)
      .then( data => res.send({ data}) )
      .catch(next);
  });
}

/* Usage
// Execute the below function on server using this API and get results.

function toBeExecutedOnServer(){
  return 'Process Id is ' + process.pid;
}

function toBeExecutedOnServer2(){
  return Promise.resolve().then(function(){ return {pid: process.pid } })
}

request.post( '/__reflection', { json: true, body: toBeExecutedOnServer.toString() }, console.log )

*/