Fetch GET Request with custom headers ReactJS

Question

I am trying to send a GET request to a API but when i add custom headers in the code somthing strange happens. Somewhere the request method changes to OPTIONS when it reaches th

Answer 1

You probably want to install the cors npm package https://www.npmjs.com/package/cors on the server where you have your http://localhost:8080/api/app Node app running.

https://developer.mozilla.org/en-US/docs/Web/HTTP/Access_control_CORS#Preflighted_requests has details about what’s happening here: Your appID and authorizationkey request headers are triggering your browser to send a CORS preflight OPTIONS request before sending the GET.

To handle that OPTIONS request, you can install the cors npm package and follow the instructions at https://www.npmjs.com/package/cors#enabling-cors-pre-flight to configure it:

var express = require('express')
  , cors = require('cors')
  , app = express();
app.options('*', cors()); // include before other routes
app.listen(80, function(){
  console.log('CORS-enabled web server listening on port 80');
});

Answer 2

The accepted answer game me the solution, i am not using a nodeJS backend but plain Nginx with php-fpm.

But the answer explains how a request with custom header wil always first do a OPTIONS request to verify the acceptance of the set header names, so i had to change the response in the webserver to give a 204 code back with te right headers included. without it would hit my PHP code where authentication would fail and result in a 403 code because of the absence of the headers with the content and request method used.

This is what i added to the Nginx host to make it work:

location ~ \.php$ {
             add_header 'Access-Control-Allow-Origin' "*";
             add_header 'Access-Control-Allow-Methods' 'GET, POST, OPTIONS, DELETE, PUT';
             add_header 'Access-Control-Allow-Headers' 'appID,authorizationkey';

             if ($request_method = 'OPTIONS') {
                return 204;
             }
}

I know that its far from perfect but for now it made it work. and again thanks for pointing me into the right direction.