CORS, also known as Cross-Origin Resource Sharing, should be enabled if you want to make a request between your client and server when they are on different URLs.
Let us consider client to be on http://localhost:5500 and the server on http://localhost:5000. Now if you try to make a request from your client to the server you will get the error stating that blocked by the CORS policy.
How To Enable CORS?
We will use cors, a node.js package to enable CORS in express Node.js Project.
Project Setup and Module Installation:
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Step 1: Create a Node.js application and name it gfg-cors using the following command.
mkdir gfg-cors && cd gfg-cors npm init
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Step 2: Install the dependency modules using the following command.
npm i express cors
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Step 3: Create client directory and server.js file in the root directory. Then create index.html and script.js in the client directory.
Project Directory: It will look like this.
Example:Write down the following code in the index.html, script.js, and server.js files.
<!DOCTYPE html> <html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content=
"width=device-width, initial-scale=1.0">
<title>gfg-cors</title>
<script src="script.js"></script>
</head>
<body>
</body>
</html>
|
.then((res) => res.json()) .then((gfg_articles) => console.log(gfg_articles)); |
// Requiring module const express = require('express');
const cors = require('cors');
// Creating express app object const app = express(); // CORS is enabled for all origins app.use(cors()); // Example api app.get('/gfg-articles',
(req, res) => res.json('gfg-articles'));
// Port Number const port = 5000; // Server setup app.listen(port, () => `Server running on port ${port}`); |
Note: If you want to allow the selected origins to access your site then you need to configure cors as shown below.
// Requiring module const express = require('express');
const cors = require('cors');
// Creating express app object const app = express(); // CORS is enabled for the selected origins let corsOptions = { }; // Using cors as a middleware app.get('/gfg-articles',cors(corsOptions),
(req,res) => res.json('gfg-articles'))
// Port number const port = 5000; // Server setup app.listen(port, () => `Server running on port ${port}`); |
If you just want to allow a particular origin to access your site, then corsOptions will be as follows:
let corsOptions = {
origin: 'http://localhost:5500'
};Step to run the application: Run the server.js using the following command.
node server.js
Output: Open index.html and then check the following output in the console.