Adding CORS headers to my NodeJS ExpressJS API but not working

Question

I have this API that I have created that is called from an angularJS app through a POST request. Everything is working fine except that, because the API and the app are not hosted on the same server, I have this Cross-Origin Resource Sharing (CORS) mechanism blocking the post request, unless I activate the CORS add-on in Chrome, which I would like to avoid.

Apparently, the solution lies in the headers, and I have found some very promising information, but there is something I must be doing wrong because I can't seem to make it work.

Here is my code:

parentheses.js (where my post request happens)

const parenthesesChecker = require('./checker.js');

const express = require('express'), bodyParser = require('body-parser');
const router = express.Router();

router.use(bodyParser.json());

router.post('/', (req, res, next) => {
  res.setHeader('Access-Control-Allow-Origin', '*');
  res.setHeader('Access-Control-Allow-Methods', 'GET, POST');
  res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type');
  const stringCheck = ({
    string: req.body
  });
  if (parenthesesChecker(stringCheck.string.string).result === true) {
    res.status(200).json({
      "isValid": true
    });
  } else {
    res.status(200).json({
      "isValid": false,
      "errorDetails": {
          "preceedingParentheses": `${parenthesesChecker(stringCheck.string.string).preceeding}`,
          "erroneosParentheses": `${parenthesesChecker(stringCheck.string.string).erroneos}`
      }
    });
  };
});

module.exports = router;

app.js

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

const parenthesesRoutes = require('./parentheses');
app.use('/parentheses', parenthesesRoutes);

module.exports = app;

server.js

const http = require('http');
const app = require('./app')

const port = process.env.PORT || 3000;

const server = http.createServer(app);
server.listen(port);

When I try to use the app that makes the post request to the API, without activating the CORS add-on in my chrome browser, I get this error message in the console:

Access to XMLHttpRequest at 'https://parentheses-api.herokuapp.com/parentheses' from origin 'http://127.0.0.1:8080' has been blocked by CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource.

Adding CORS headers to my NodeJS ExpressJS API but not working

0 Answers