Andrew Pollack's Blog

Technology, Family, Entertainment, Politics, and Random Noise

- CORRECTION - Having just wasted a good bit of the afternoon, here's a technote on setting cookie expiration dates for IE

By Andrew Pollack on 02/24/2008 at 12:41 PM EST

* Corrected on Feb 24.

Many of you super JavaScript programmers already know this, but since I didn't have it quite right I thought I'd post it here so that if someone else is searching for information they'll have an easier time of it.

When you set a cookie in JavaScript, you make it 'permanent' (make it last through browser restarts) by setting a parameter called "expires". There are web pages all over the place that will tell you about lots of different formats you can set that expiration date in. Many of them work for Mozilla and other other browsers.

For Internet Explorer -- particularly for Internet Explorer version 7 -- there is only one format that actually works in a reliable way. There are technotes that claim you can use "14 day" or "1 year" or "2 hours". There are technotes out there that claim you can use a unix numeric time value (the number of seconds since 1/1/1970). While these may work for other browsers, you will waste your time if you try them with IE7. Worse, it will not give you any error or indication that it failed. It simply won't keep the cookie if you restart the browser.

Yes, sometimes other formats work. Not reliably however. The "Correct" format* according to Microsoft is:


The values are as follows:

DAY = Mon, Tue, Wed, Thu, Fri, Sat, Sun
MON = A Three Letter Version of the Month (Jan, Feb, ...)
DD = A two digit number representing the Day
YYYY = A four digit number representing the Year
HH = A two digit number representing the hour, in 24 hour time format.
MM = A two digit number representing the Minute
SS = A two digit number representing the Second
GMT = Always set dates in GMT time, and include GMT on the string

For all numeric values, you MUST use both digits. Pad with a leading zero as needed

* I have noted that if you tell Microsoft's JavaScript implementation to output Date.toGMTString() you get this in the same format but without dashes between the date components:


Since the common JavaScript way to do this is to use a data object this way, it is safe to assume this is also supported. In my testing, it does work.

There are  - loading -  comments....

Other Recent Stories...

  1. 09/04/2018With two big projects on hold, I suddenly find myself very available for new short and long term projects. In twenty five years, I don't think I've ever written an entry like this, but if you need the kind of work I do now would be a great time to get in touch. Both of the big projects I had lined up for late summer and early fall have been placed on hold and will be that way for a while. With the kids now all off at college and careers, I'm open to more travel than such than I have been in decades, but unless something else comes along, I'll be here working on updates to Second Signal and other things that ...... 
  2. 07/13/2018Who is HCL and why is it a good thing that they are now the ones behind Notes and Domino?We need to address some biases here. IBM has made a deal under which the Notes & Domino software and intellectual property is now being developed and maintained by HCL America. HCL America is part of the very large "HCL Technologies" company that has grown from its roots in India to become an 8 Billion Dollar company with a global presence in the IT Industry. You could be excused for initially believing, as many people do when they hear this, that "they've outsourced the code to India where they'll milk it ...... 
  3. 03/21/2018Domino Apps on IOS is a Game Changer. Quit holding back.BOOM. This will be as important for the platform as Traveler. If your company has ditched Notes and Domino, I feel sorry for you. For companies that do use Notes/Domino this is a game changer and Apple should be paying attention. Here's why: There are hundreds of little Notes client applications you'd never spend the time and money to build and deploy for your internal user base on IOS that we use Notes for all the time (those of us still using it). Now, those are suddenly ALL available on the iPad. ...... 
  4. 02/15/2018Andrew’s Proposed Gun Laws 
  5. 05/05/2016Is the growing social-sourced economy the modern back door into socialism? 
  6. 04/20/2016Want to be whitelisted? Here are some sensible rules for web site advertising 
  7. 12/30/2015Fantastic new series on Syfy called “The Expanse” – for people who love traditional science fiction 
  8. 10/20/2015My suggestion is to stay away from PayAnywhere(dot)com  
  9. 08/07/2015Here is one for you VMWARE gurus - particularly if you run ESXi without fancy drive arrays 
  10. 08/06/2015The Killer of Orphans (Orphan Documents) 
Click here for more articles.....

pen icon Comment Entry
Your Name
*Your Email
* Your email address is required, but not displayed.
Your thoughts....
Remember Me  

Please wait while your document is saved.