CrossDomain.js

var requests = require('superagent');

var fetch = function(url, options) {
  let method = options.method;
  return new Promise((resolve, reject) => {
    requests[method](url)
      .end((err, res) => {        
        if (err) {
          reject(err);
        }
        else {
          resolve(res);
        }
      })
  }) 
}

fetch('http://localhost:8888', {method: 'patch'})
  .then(res => console.log(`SUCCESS: {JSON.stringify(res.body)}`))
  .catch(err => {
    if (err.crossDomain) {
      console.error('Cross domain error!!!')
      fetch('http://localhost:8888', {method: 'put'})
        .then(res => console.log(`SUCCESS: {JSON.stringify(res.body)}`))
        .catch(err => {
          console.error('¯\_(ツ)_/¯');
        })
    }
  })