How to remove a cookie by using Javascript?

Question

How to remove the cookie set by

javascript:void(document.cookie=”PREF=ID=20b6e4c2f44943bb:U=4bf292d46faad806:TM=1249677602:LM=1257919388:S=odm0Ys-53ZueXfZG;path=/; domain=.google.com”);

The following statement doesn't work.

javascript:void(document.cookie=”PREF=ID=20b6e4c2f44943bb:U=4bf292d46faad806:TM=1249677602:LM=1257919388:S=odm0Ys-53ZueXfZG;expires=Thu, 01 Jan 1970 00:00:00 GMT;path=/; domain=.google.com”);

What's wrong with the removal code?

Answer 1

Your cookie domain is .google.com, if you're not actually running the code from that domain you will not be able to modify the cookie.

Answer 2

Trick is right... in particular you need to put any past-value in the expires header. (These days you'd use a full-year, though; the two-digit format goes back to the early Netscapes only.)

Also ensure you don't use smart quotes like in your quote above.

javascript:alert(document.cookie='PREF=X;path=/;domain=.google.com;expires=Sat, 01-Jan-2000 00:00:00 GMT');

Note that the format produced by Date.toGMTString is not the same as the date format required by the cookie specification, although it does still work in many browsers.

Answer 3

Agreed, @bobince. The official documentation says to use Date.toUTCString() for cookie expiration dates.

I am 95% sure that you must set an expiration date when creating the cookie crumb if you want to force its removal later. A cookie crumb created without an explicit expiration date is a session cookie (crumb) by default, which means that it is not removed until the browser is closed. I recall trying to expire a session cookie to no avail, in the past.

If you do set an expiration date on the cookie crumb in the first place, remember that you can use a variable for the new expiration date.

// assuming a non-session cookie crumb called "someCrumbName" exists:
var now = new Date();
var expirationDate = new Date();
var someValue = "foo";

// set the expiration date to a week ago and delete the cookie
expirationDate.setDate(now.getDate() - 7);
document.cookie = "someCrumbName=" + someValue + ";expires=" + expirationDate.toUTCString();

Answer 4

Why don't you just stick with one question or figure it out for yourself rather than keep posting your problems every few minutes?

e.g. https://stackoverflow.com/questions/1802210/how-to-recover-google-classic-design-from-its-new-design

How to reverse the effect of the following execution by using Javascript?

Answer 5

Thu, 01-Jan-70 00:00:01 GMT

Set time one second after midnight