Answers for "from origin 'http://localhost:3000' has been blocked by CORS policy: Request header field access-control-allow-origin is not allowed by Access-Control-Allow-Headers in preflight response."

has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response.

response.setHeader("Access-Control-Allow-Origin", "*");
response.setHeader("Access-Control-Allow-Credentials", "true");
response.setHeader("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
response.setHeader("Access-Control-Allow-Headers", "Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers");

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 

 AppHttpMiddlewareCors::class,

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

'cors' => AppHttpMiddlewareCors::class,



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

has been blocked by CORS policy: Request header field content-type is not allowed by Access-Control-Allow-Headers in preflight response

var dataToSend = ' {"firstname": "' + form.vals().FirstName + '","lastname": "' + form.vals().LastName + '","email": "' + form.vals().Email + '"}';
var xhr = new XMLHttpRequest();
xhr.open('POST', 'https://exampleurl');
xhr.setRequestHeader('Content-type','application/json');
xhr.send(dataToSend);
xhr.onreadystatechange = function() {
  if (this.readyState == 4 && this.status == 200) {
	console.log(this.responseText);
  }
};



xhr.setRequestHeader("Access-Control-Allow-Origin", "*");
xhr.setRequestHeader("Access-Control-Allow-Credentials", "true");
xhr.setRequestHeader("Access-Control-Allow-Methods", "GET,HEAD,OPTIONS,POST,PUT");
xhr.setRequestHeader("Access-Control-Allow-Headers", "Access-Control-Allow-Headers, Origin,Accept, X-Requested-With, Content-Type, Access-Control-Request-Method, Access-Control-Request-Headers");