Entry

How can I read and write cookies with client side Javascript?

How can I delete a cookie?

Nov 21st, 2001 05:59
Thor Larholm, Martin Honnen, http://tech.irt.org/articles/js064/index.htm

Basically you just set
  document.cookie = 'cookieName=cookieValue'
to set a cookie and then parse
  document.cookie
to read a cookie.
The following functions setCookie and getCookie do the work of setting 
and getting a cookie properly; setCookie takes at least two arguments, 
the cookie name and the cookie value, and 4 optional arguments the 
first being an expires Date object, the second be a string path, the 
third being a string domain, and the last being a boolean value secure 
(for HTTPS cookies only):
function setCookie (cookieName, cookieValue, expires, path, domain, 
secure) {
  document.cookie = 
    escape(cookieName) + '=' + escape(cookieValue) 
    + (expires ? '; EXPIRES=' + expires.toGMTString() : '')
    + (path ? '; PATH=' + path : '')
    + (domain ? '; DOMAIN=' + domain : '')
    + (secure ? '; SECURE' : '');
}
function getCookie (cookieName) {
  var cookieValue = null;
  var posName = document.cookie.indexOf(escape(cookieName) + '=');
  if (posName != -1) {
    var posValue = posName + (escape(cookieName) + '=').length;
    var endPos = document.cookie.indexOf(';', posValue);
    if (endPos != -1)
      cookieValue = unescape(document.cookie.substring(posValue, 
endPos));
    else
      cookieValue = unescape(document.cookie.substring(posValue));
  }
  return cookieValue;
}
Examples of use:
  // set a session cookie which expires after the browser is closed
  setCookie ('cookieName', 'cookieValue');
  // set a cookie which expires after 24 hours
  var now = new Date();
  var tomorrow = new Date(now.getTime() + 1000 * 60 * 60 * 24)
  setCookie ('cookieName', 'cookieValue', tomorrow);
  // set a cookie with a path
  setCookie ('cookieName', 'cookieValue', null, '/')
To delete a cookie you just set it with an expires date in the past:
  var now = new Date();
  var yesterday = new Date(now.getTime() - 1000 * 60 * 60 * 24);
  setCookie('cookieName', 'cookieValue', yesterday);