CORS policy: Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on the requested resource. code example

Example 1: 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.

My issue was the remote server not responding to OPTIONS requests, 
so after fiddling about with requests and headers for what seemed 
like ages I resolved it by removing the headers 
Content-Type and Access-Control-Allow-Origin

Example 2: laravel Response to preflight request doesn't pass access control check: No 'Access-Control-Allow-Origin' header is present on

Step 1 : Create Cors middleware.
php artisan make:middleware Cors

Step 2 : Add below lines in handle function before return.
  //header('Access-Control-Allow-Origin:  *');
header('Access-Control-Allow-Origin:  http://localhost:4200');
header('Access-Control-Allow-Headers:  Content-Type, X-Auth-Token, Authorization, Origin');
header('Access-Control-Allow-Methods:  POST, PUT');

Step 3 : Register the middileware in app/Http/Kernel.php file
  
  Add below line in $middleware array 

 \App\Http\Middleware\Cors::class,

Step 4 : Now we have to call the middleware in app/Http/Kernel.php file
  Add below line in $routeMiddleware array 

'cors' => \App\Http\Middleware\Cors::class,



Using the * works rather than the host origin. Was missing the Cors.php middleware in the array as well

Example 3: viacep Response to preflight request doesn't pass access control check: Redirect is not allowed for a preflight request.

npm install --save cep-promise

...

import * as cep from 'cep-promise'

cep('05010000')
  .then(console.log)