I developed a frontend using react.js and an API server using express.js. To handle CORS, I utilized the cors package as shown below:
var passport = require("passport");
const express = require('express');
const cors = require('cors');
const app = express();
app.use(cors());
app.use('/route1', passport.authenticate('jwt', {session: false}), route1)
app.use('/route2', passport.authenticate('jwt', {session: false}), route2)
app.use('/route3', passport.authenticate('jwt', {session: false}), route3)
app.use(function(req, res, next) { /* catch 404 and forward to error handler */
next(createError(404));
});
app.listen(app.get('port'), () => {
logger.info('Server started')
})
All routes function correctly, except when multiple requests are made consecutively for the same route. For instance:
POST example.com/route1
GET example.com/route1
When this occurs, I receive the error
No 'Access-Control-Allow-Origin' header is present on the requested resource.POST example.com/route1
GET example.com/route1/example
it functions properly.
Both servers are hosted on an apache webserver. The backend server is accessed via https, which redirects it to the nodejs server operating on http.
What am I missing? Thank you.
edit: here is a snippet of route1:
const express = require('express')
const router = express.Router()
const errors = require('./error_handler');
router.post('/', async (req, res, next) => {
const result =
/* DB Middleware */
.catch((err) => errors.errorHandler(err,res))
if(!res.headersSent) /* Adding this condition to check if errorHandler() already sent an error response */
res.send(result);
})
router.get('/', async (req, res, next) => {
if(req.query.course === undefined)
res.send(400);
let result =
/* DB Middleware */
.catch((err) => errors.errorHandler(err,res))
if(!res.headersSent)
res.send(result)
})
module.exports = router