Node.js : POST - Request Method: OPTIONS Status Code: 403 Forbidden

Question

We have the following setup :

Front end code : REACT (Hosted using express js) (lets call this www.domainA.com)
Backend        : .NET WEB API (Hosted in IIS          


        

Answer 1

The answer from Jannes Botis explains well the Preflighted mechanism. I'm just adding the code I'm using to solve this issue on Node.js / Express

const express = require('express');
const app = express();

app.use((req, res, next) => {
  res.setHeader('Access-Control-Allow-Origin', 'http://www.domainA.com');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST, DELETE, OPTIONS');
  res.setHeader(
    'Access-Control-Allow-Headers',
    'Origin, X-Requested-With, Content-Type, Accept, Authorization'
  );
  next();
});

// All OPTIONS requests return a simple status: 'OK'
app.options('*', (req, res) => {
  res.json({
    status: 'OK'
  });
});

app.get('/', ...);

app.post('/api/postdataoperation', ...);