post-react.js

// webpack 
presets: ['stage-0', 'es2015', 'react']

// saga fetch  
const { loginEmail, loginPwd } = request.payload;
  
let postLoginSubmitOptions = {
  method: "POST",
  headers: new Headers({
    'Accept': 'application/json',
    'Content-type': 'application/x-www-form-urlencoded'
  }),
  mode: 'no-cors',
  body: JSON.stringify({
    loginEmail: "[email protected]",
    loginPwd: "passwordkdhfhf"
  })
};

console.log(postLoginSubmitOptions.body) // { "loginEmail" : "[email protected]", "loginPwd" : "passwordkdhfhf" }
  
const response = yield call(fetch, `http://www.example.com/register`, postLoginSubmitOptions);

// express server side

router.post('/register', bodyParser.urlencoded({ extended: false }), function(req, res, next) {
  console.log('registering user');
  res.setHeader('Access-Control-Allow-Origin', 'http://localhost:3333');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE');
  res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
  res.setHeader('Access-Control-Allow-Credentials', true);
  
  console.log(`incoming req below`);
  console.log(req.body); // { '{ "loginEmail" : "[email protected]", "loginPwd" : "passwordkdhfhf" }' : '' }
  
// app.js
  
  app.use(bodyParser.json());