CORS Cheat Sheet for Express + TypeScript

CORS Cheat Sheet for Express + TypeScript.md

1. Install cors package and its TypeScript types:

npm install cors
npm install --save-dev @types/cors

2. Update the entry point of your Express app to allow your server to use cors middleware. Configure your CORS options with the origins you would like to allow.

import express from 'express';
import cors from 'cors';

const app = express();

// Add a list of allowed origins.
// If you have more origins you would like to add, you can add them to the array below.
const allowedOrigins = ['http://localhost:3000'];

const options: cors.CorsOptions = {
  origin: allowedOrigins
};

// Then pass these options to cors:
app.use(cors(options));

app.use(express.json());


app.listen(5000, () => {
  console.log('Express server listening on port 5000');
});

THANK YOU 👍

thank you

perfect! thankyou

Thanks, I resolved the error but CORS is not preventing it properly, do you have any idea?

I have allowed only one origin "http://localhost:3000", and I am testing with the "http://localhost:450" URL from Postman, by changing "Origin".

Here is my sample cURL, localhost:8936 is my API endpoint

curl --location 'localhost:8936' \ --header 'Origin: localhost:450'

It is still getting a 200 OK response.

Very useful! Thanks.