What is CORS?
Cross-Origin Resource Sharing (CORS) is a standard that allows a server to relax the same-origin policy. This is used to explicitly allow some cross-origin requests while rejecting others.
From Mozilla https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS/Errors
Basically what it means is that, if you are on site aorborc.com and trying to request information from doreorf.com via client side javascript, the browser will through this error.
Sample Errors
The value of the 'Access-Control-Allow-Origin' header in the response must not be the wildcard '*' when the request's credentials mode is 'include'. The credentials mode of requests initiated by the XMLHttpRequest is controlled by the withCredentials attribute.
It does not have HTTP ok status.
How to fix it
If you are a nextjs/vercel user like us, when you respond from your server, just add the below code inside your API function
export default async function handler(req, res) {
res.setHeader("Access-Control-Allow-Credentials", true);
res.setHeader(
"Access-Control-Allow-Origin",
req.headers.origin ? req.headers.origin : "*"
);
res.setHeader(
"Access-Control-Allow-Methods",
"GET,OPTIONS,PATCH,DELETE,POST,PUT"
);
res.setHeader(
"Access-Control-Allow-Headers",
"X-CSRF-Token, X-Requested-With, Accept, Accept-Version, Content-Length, Content-MD5, Content-Type, Date, X-Api-Version"
);
//For CORS
if (req.method === "OPTIONS") {
res.status(200).end();
return;
}
//Your rest of the code below
res.status(200).json({result:"Ok"});
}
The above code should avoid CORS error for your custom next js server.