Ninedays Blog

Typically when I'm working on a site everything has either a .php extension or is Apache rewrite_moded to a PHP file.

Though this is an obvious thing for me to do it isn't so obvious for some of the people I've worked with or some clients whom I've needed to make updates for. So when I suddenly needed to retrieve a query string and make it available site wide I had to go back to cookies with JavaScript.

First I searched the web for the best functions to set, get and delete my cookies. No one site seemed to get all of it right so I had to do a little leg work of my own.
It's been probably 3 years since I set a JavaScript cookie by hand. Back in my INT220 class at AI I believe (Hi Dale and thanks for all the smarts you done gave me!)

Before you can work with a JavaScript cookie, you have to set one, which is why part one of our lesson is:

Setting a Cookie with JavaScript

Broken down setting cookies with JavaScript is easy-peasy:

JavaScript

document.cookie = "CookieName=CookieValue; expires=Monday, 31-Dec-2010 23:59:59 GMT; path=/; domain=.example.com; secure";

That will set the cookie CookieName with the value CookieValue which will expire at the end of 2001 set to the root path and the domain example.org (including sub domains) and it's secure (https),

Now that's great but a function, that's even better. Especially since everything after the key=value pair (in this case CookieName=CookieValue) is optional.

I saw plenty of functions where if you passed expires as empty it would set the cookie to expire in a day or a couple hours but I want to be able to set that individually or have the cookie default to be a session cookie. So I found a function and modified it into this:

JavaScript

function setCookie(name, value, expires, path, domain, secure) {
  var curCookie = name + "=" + escape(value) +
      ((expires) ? "; expires=" + expires.toUTCString() : "") +
      ((path) ? "; path=" + path : "") +
      ((domain) ? "; domain=" + domain : "") +
      ((secure) ? "; secure" : "");
  document.cookie = curCookie;
}

The name of the cookie and value is pretty self explanatory so we'll skip straight to the expire parameter.

Expire

As I said before if you pass nothing or an empty/null value as the expire parameter it will be a session cookie, one that expires when the browser is closed. To set the expiration time you need to pass a date which will be transformed into the appropriate format inside the function.

So if you want to set a cookie that will expire in 22 hours, try:

JavaScript

var expDate = new Date();
expDate.setHours( parseInt(expDate.getHours()) + 22 );
setCookie('CookieName', 'CookieValue', expDate) ;

Here's a quick synopsis of how to set other relative dates:

• 45 seconds in the future
  expDate.setSeconds( parseInt(expDate.getSeconds()) + 45 );
• 30 minutes in the future
  expDate.setMinutes( parseInt(expDate.getMinutes()) + 30 );
• 5 hours in the future
  expDate.setHours( parseInt(expDate.getHours()) + 30 );
• 7 days in the future
  expDate.setDate( parseInt(expDate.getDate()) + 7 );
• 6 months in the future
  expDate.setMonth( parseInt(expDate.getMonth()) + 6 );
• 1 year in the future
  expDate.setYear( parseInt(expDate.getYear()) + 1 );

Easy enough!

Path

By default a cookie with no value set for path will set the cookie relative to the path you are in. So if the cookie is set in the example.com/test/javascript/index.html page the cookie will be set with a path of /test/javascript/
I usually force my cookies with a path to the root / to ensure I don't have problems with the cookie anywhere on the site.

Domain

There's multiple ways to set this, though I stick with the default (which is whatever domain you are in when you set the cookie.)

• example.com
• .example.com - (includes all sub domains)
• subdomain.example.com

If you need to access this cookie from sub domains you need to make sure that the . precedes the domain name. As a rule of thumb, omit the www.

Secure

I don't do a lot with SSL but if I needed to set a cookie in teh secure portion of https://example.com you would have to pass secure (as itself, there is no pairing here and it is not boolean) to ensure there are no problems.

Download

Download the complete JavaScript file functions.cookies.js

Continue on to page 2: deleting, updating and retrieving JavaScript cookies...