Creating A Javascript Cookie On A Domain And Reading It Across Sub Domains

Have you ever wanted to store information in a cookie using JavaScript and then access that information across multiple subdomains of a website? In this article, we'll show you how to do just that.

To create a cookie in JavaScript that can be accessed across subdomains, you need to set it on the main domain. This involves configuring the cookie's domain property to be the root domain, which will make it available to all subdomains. Here's how you can create a JavaScript cookie on a domain and read it across subdomains:

Step 1: Create a Cookie:

To create a cookie, you can use the document.cookie property in JavaScript. Here's an example code snippet that sets a cookie named "exampleCookie" with a value of "exampleValue" for the root domain:

document.cookie = "exampleCookie=exampleValue; domain=.yourdomain.com; path=/;";

In this code snippet, replace ".yourdomain.com" with your actual domain name. By setting the domain property to ".yourdomain.com", the cookie will be accessible across all subdomains of your website.

Step 2: Read the Cookie Across Subdomains:

To read the cookie from a subdomain, you need to ensure that the domain property is set correctly. Here's an example code snippet that reads the "exampleCookie" on a subdomain:

let cookies = document.cookie.split('; ');
cookies.forEach(cookie => {
    let [name, value] = cookie.split('=');
    if (name === 'exampleCookie') {
        console.log(`Value of exampleCookie: ${value}`);
    }
});

By setting the domain property as ".yourdomain.com" when creating the cookie, it will be included in the HTTP request headers for all requests to any subdomain, allowing you to access it from any subdomain.

Step 3: Additional Considerations:

- Remember that cookies have limitations, such as size constraints and security considerations. Avoid storing sensitive information in cookies.
- Ensure that the path property of the cookie is set to "/" to make it accessible across the entire domain.
- Make sure to handle cookie expiration and deletion as needed to manage user preferences and data privacy.

By following these steps, you can create a JavaScript cookie on a domain and read it across subdomains, enabling seamless data sharing and user experiences across different parts of your website. Remember to test the functionality thoroughly to ensure it works as expected in your specific setup. Happy coding!