Creating a JavaScript cookie on a domain and reading it across sub domains

Question

Below is a JavaScript cookie that is written on the user\'s computer for 12 months.

After we set the cookie on our main domain such as example.com, shou

Answer 1

You want:

document.cookie = cookieName +"=" + cookieValue + ";domain=.example.com;path=/;expires=" + myDate;

As per the RFC 2109, to have a cookie available to all subdomains, you must put a . in front of your domain.

Setting the path=/ will have the cookie be available within the entire specified domain(aka .example.com).

Answer 2

You can also use the MDN JavaScript Cookie Framework and do:

docCookies.setItem('HelloWorld', 'HelloWorld', myDate, '/', 'example.com');

Answer 3

Just set the domain and path attributes on your cookie, like:

<script type="text/javascript">
var cookieName = 'HelloWorld';
var cookieValue = 'HelloWorld';
var myDate = new Date();
myDate.setMonth(myDate.getMonth() + 12);
document.cookie = cookieName +"=" + cookieValue + ";expires=" + myDate 
                  + ";domain=.example.com;path=/";
</script>

Answer 4

Here is a working example :

document.cookie = "testCookie=cookieval; domain=." + 
location.hostname.split('.').reverse()[1] + "." + 
location.hostname.split('.').reverse()[0] + "; path=/"

This is a generic solution that takes the root domain from the location object and sets the cookie. The reversing is because you don't know how many subdomains you have if any.