CORS Issues with Google Authentication

Question

I have been implementing Google Auth on my MERN stack web application. However, I encountered an error: 'Redirected from 'http://localhost:5000/api/v1/auth/google' from origin 'http://localhost:5173' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource.' even tho i've already set cors on my server.

const cors = require("cors");
app.use(cors());

Answer 1

You'll need to whitelist certain origins, otherwise CORS will deny all traffic that doesn't match the domain:

See https://github.com/expressjs/cors#configuring-cors-asynchronously

const whitelist = config.getWhiteList(); // ["http://localhost:5173"]

const corsConfig = cors({
  origin: (origin, callback) => {
    if (!origin || whitelist.includes(origin)) {
      callback(null, true);
    } else {
      callback(new Error('Not allowed by CORS'));
    }
  },
});

app.use(corsConfig);