CORS Policy in Node.js and Express.js

Welcome to the lesson 11 of our Book Store MERN Stack project. In this lesson, we will be discussing about CORS policy in Node.js and Express.js.

CORS stands for Cross-Origin Resource Sharing. It is a security feature implemented in web browsers to prevent websites from making requests to a different domain. This is important for protecting sensitive data and resources on the web.

When building a web application using Node.js and Express.js, you may encounter issues with CORS policy when making requests from the client-side to the server-side. This is because by default, Express.js does not allow cross-origin requests for security reasons.

To enable cross-origin requests in Express.js, we can use the ‘cors’ package. First, we need to install the ‘cors’ package using npm:

  
    npm install cors
  

Once the ‘cors’ package is installed, we can use it in our Express.js application by including the following code:

  
    const express = require('express');
    const cors = require('cors');

    const app = express();

    app.use(cors());
  

By including the ‘cors’ package and using the app.use(cors()) middleware in our Express.js application, we can now allow cross-origin requests from the client-side to the server-side.

It is important to note that when using the ‘cors’ package, we can also specify which origins are allowed to make requests to our server by passing in an options object to the cors() middleware. This allows us to have more control over the cross-origin requests in our application.

Overall, understanding and implementing CORS policy in Node.js and Express.js is crucial for building secure and functional web applications. By using the ‘cors’ package, we can easily enable cross-origin requests and protect our server-side resources.

Thank you for reading this lesson on CORS policy in Node.js and Express.js. Stay tuned for more lessons in our Book Store MERN Stack project!